PEDIATRIC EMERGENCY ROOM REVISITS IN URBAN ONTARIO:

DOES BEING AN IMMIGRANT MATTER?

By

Natasha Ruth Saunders MSc MD FRCPC

A thesis submitted in conformity with the requirements for the degree of Master of Science

(Clinical Epidemiology and Health Care Research)

Graduate Department of the Institute for Health Policy, Management and Evaluation

University of Toronto

© Copyright by Natasha Saunders 2015

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Pediatric emergency room revisits in urban Ontario: does being an immigrant matter?

Natasha Ruth Saunders MSc MD FRCPC

Master of Science (Clinical Epidemiology and Health Care Research)

Graduate Department of the Institute for Health Policy, Management and Evaluation

University of Toronto

2015

Abstract

Objectives: To test the association of unscheduled 7-day emergency department (ED) revisits and

immigrant status for all children living in urban Ontario and within subgroups of immigrant children.

Methods: Population-based cohort study using linked health administrative and demographic

datasets of immigrant and non-immigrant children in urban Ontario, who visited an ED between

April 2003 and March 2010 (n = 3322901). Associations were tested using logistic regression

models.

Results: Recent immigrants had a higher odds of ED revisit compared with non-immigrants (OR

1.07; 95% CI 1.05-1.09). In the adjusted model, this relationship disappeared. Within immigrants,

the odds of revisit was not different between immigrant classes or by region of origin but

immigrants whose native tongue was not English or French had a higher odds of revisiting the ED in

adjusted models (AOR 1.05; 95% CI 1.01-1.09).

Conclusions: Immigrant children are not more likely to revisit the ED, although within immigrants,

language proficiency is important.

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Acknowledgments

I would like to thank my thesis committee, Drs. Patricia Parkin and Teresa To for their guidance and

expertise with the development of this thesis. In particular, I would like to thank Dr. Astrid

Guttmann for her invaluable mentorship and belief in my potential throughout the past two years.

She has been incredible, allowed me share in her passion for child health services research, and

provided me with countless opportunities for career development. Thank you to Qi Li for cutting

the data and answering my questions about data analysis.

I would like to thank the Research Institute and the Academic General Pediatrics Fellowship Program

at The Hospital for Sick Children for the Restracomp Award that supported me financially and

allowed me dedicated research time to pursue my studies.

Finally, I would like to thank my family for their unconditional love and support. I am particularly

grateful to my parents, Lynn and Norman Saunders, for teaching in me the value of integrity and

commitment, and to my husband, Justin Fluit, and children Nathan and Hailey Fluit for their

encouragement, and for reminding me each day just how fortunate I am.

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Table of Contents

PAGE

1.0 REVIEW OF THE LITERATURE 1

1.1 Introduction 1

1.2 Immigration in Canada 1

1.3 The cost and burden of emergency department revisits 4

1.4 Health services access, use, and safety for immigrants 6

2.0 THESIS OBJECTIVES AND HYPOTHESES 10

2.1 Rationale and relevance 10

2.2 Research questions 10

2.3 Specific objectives and hypotheses 10

3.0 METHODS 12

3.1 Overview of methods 12

3.2 Research ethics approval 12

3.3 Data sources 12

3.4 Study population 14

3.5 Outcome variables 14

3.6 Independent variables 15

3.7 Covariates 16

3.8 Statistical analysis 18

4.0 RESULTS 21

4.1 Children living in a Census Metropolitan Area visiting an Ontario ED 2003-2010 21

4.2 Overall composition of population based on Immigrant status 21

4.3 Baseline characteristics of cohort who visited an ED 21

4.4 Overall outcomes: revisits, revisits leading to admission, revisits with a worse 25

CTAS score

4.5 Primary outcome: ED revisits 26

4.5.1 Association of immigrant status with ED revisits 26

4.5.2 Association of immigrant category, native language, official language 32

of country of birth, and region of origin with ED revisits

4.5.3 Assessment of multi-collinearity of independent variables for ED revisits 35

4.6 Secondary outcome: revisits leading to admission 35

4.6.1 Association of immigrant status with revisits leading to admission 36

4.6.2 Association of immigrant category, native language, official language 41

of country of birth, and region of origin with revisits leading to admission

4.6.3 Assessment of multi-collinearity of independent variables for visits 44

leading to admission

4.7 Secondary outcome: revisits leading to a worse CTAS score on the revisit 45

4.7.1 Association of immigrant status with revisits leading to worse 45

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CTAS score

4.7.2 Association of immigrant category, native language, official language 50

of country of birth, and region of origin with revisits leading to worse CTAS score

4.7.3 Assessment of multi-collinearity of independent variables for revisits 51

leading to worse CTAS score on the revisit

5.0 DISCUSSION 53

5.1 Key findings 53

5.2 Strengths of study 59

5.3 Limitations 60

5.4 Future directions 61

5.5 Implications 63

6.0 REFERENCES 65

7.0 APPENDICES 70

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Role of the Candidate

The candidate was involved in all aspects of the research study. With the support and guidance of

her primary supervisor, Dr. Astrid Guttmann, and thesis committee, the candidate performed the

background literature review, generated the research questions and objectives, designed the study

and analysis plan, obtained research ethics approval, performed statistical analysis on the data

provided by the analyst (Qi Li), interpreted the results, and wrote the thesis.

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List of Tables

PAGE

Table 1. Baseline characteristics of pediatric patients from CMA’s in Ontario who visited an ED from April 2003 to March 2010

23

Table 2. Baseline immigration characteristics of pediatric immigrants from CMA’s in Ontario who visited an ED from April 2003 to March 2010

24

Table 3. Revisit Characteristics 25

Table 4. Revisits to an ED for pediatric patients living in CMA’s of Ontario from April 2003 to March 2010 by immigrant status and patient and hospital characteristics

27

Table 5. Unadjusted and adjusted logistic regressions with odds ratios of ED revisits according to patient and hospital characteristics

31

Table 6. Revisits to an ED for pediatric immigrants living in CMA’s of Ontario from April 2003 to March 2010 by immigration characteristics

33

Table 7. Unadjusted and adjusted logistic regressions with odds ratios of ED revisits according to immigration characteristics

34

Table 8. Tolerance and variance inflation factors for independent variables for ED revisits 35

Table 9. Overall ED revisits leading to admission or death from April 2003 to March 2010 36

Table 10. Characteristics of pediatric patients from urban Ontario who revisited an ED and were admitted/died on the revisit according to immigrant status

37

Table 11 Unadjusted and adjusted logistic regressions with odds ratios of ED revisits leading to admission according to patient and hospital characteristic

39

Table 12 Revisits to an ED leading to admission based on immigrant characteristics 42

Table 13. Unadjusted and adjusted odds ratios of ED revisits leading to admission according to immigration characteristics

43

Table 14. Tolerance and variance inflation factors for independent variables for ED revisits leading to admission

44

Table 15. ED revisits leading to a worse CTAS score on the revisit 45

Table 16. Characteristics of pediatric patients from urban Ontario who revisited an ED and had a worse CTAS score on the revisit according to immigrant status

46

Table 17. Unadjusted and adjusted logistic regressions with odds ratios of ED revisits leading to worse CTAS score according to patient and hospital characteristic

48

Table 18. Revisits to an ED leading to a worse CTAS score on the revisit based on 50

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immigrant characteristics

Table 19. Unadjusted and adjusted odds ratios of ED revisits leading to a worse CTAS score according to immigration characteristics

51

Table 20. Tolerance and variance inflation factors for independent variables for ED revisits leading to worse CTAS score on the revisit

52

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List of Appendices

PAGE

Appendix A

Table IA. List of Census Metropolitan Areas: 2006 Canadian Census 70

Appendix B

Table IB. List of country code, region, and language information 71

Appendix C

Figure IC. Flow chart of patient exclusions for ED visits 76

Figure IIC. Flow chart of patient exclusions for ED revisits 77

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1.0 Review of the literature

1.1 Introduction

Over the last two decades, Canada has seen a considerable increase in its immigrant population with

immigrants now making up 19.8% of the total Canadian population [1, 2]. It is expected that by

2030 immigration will be the main contributing factor to Canada’s population growth [3]. Most

immigrants are either working aged accompanied by their family, or they start a family shortly after

arrival in Canada. Accordingly, children of immigrants make up a large proportion of the Canadian

population [4]. Unfortunately, there is little current knowledge about pediatric immigrant health

outcomes, and limited understanding about how pediatric immigrants use and interact with

Canada’s healthcare system. Yet this information is critical to policy makers and service providers in

the planning and delivery of safe and equitable health care. It is therefore important that we focus

our attention to this population, to determine how to best serve their health needs and plan for the

future of all Canadians.

This review attempts to examine immigration demographics in Canada, explore pediatric emergency

department (ED) revisits as a measure of health care access, quality, and safety; evaluate what is

known about use of the health care system by immigrant families in Ontario and Canada; and

examine drivers of ED use and health seeking behaviour as they relate to immigrant families. It is

hoped that this research will enrich our understanding of the complex and interconnected elements

that affect the health of pediatric immigrants, and thereby enable both planners and providers to

ensure programs and policies are in place to allow every child in Canada – regardless of where they

are born – to receive high quality and accessible health care.

1.2 Immigration in Canada

Canada ranks near the top among the world’s recipient countries for immigrants. According to

Citizenship and Immigration Canada, Canada receives approximately 250000 landed immigrants

annually [4]. Of these, approximately 160000 (64%) are Economic class, 65000 (26%) are Family

class, and 25000 (10%) are Refugee class. Children under 14 years of age account for approximately

50000 landed immigrants annually with 70-80% Economic class, 12-15% Family class, and 12-18%

Refugee class. According to the 2006 Canadian Census, 19.8% of the Canadian population is an

immigrant, the highest proportion since the 1930’s. The only other Western country whose foreign

born population exceeds that of Canada is Australia, with 22.2% immigrants [4]. The top source

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countries for permanent residents in Canada include China, the Philippines, India, Pakistan, and the

United States (US). This is notably different compared to before the 1970’s, when over 70% of

immigrants emigrated from Europe, 15% from the US, and 10% from Asia [4].

To become a landed immigrant, one must apply to become a permanent resident in one of three

major classes, including Economic, Family, or Refugee class. Economic class immigrants are selected

for their skills and ability to contribute to Canada’s economy. This class includes skilled workers,

business immigrants, provincial or territorial nominees, live-in caregivers, and the Canadian

Experience Class. Family class immigrants are those sponsored by a Canadian citizen or a

permanent resident living in Canada who is 18 years of age or over. It includes spouses and

partners, parents and grandparents, children, and nieces and nephews. Finally, Refugee class

includes government-assisted refugees, privately sponsored refugees, refugees landed in Canada,

and refugee dependents [4]. The number of people admitted to Canada each year varies, and is

dependent upon the needs of the Canadian economic environment and the need to protect others

from potential harm in their native country. Temporary foreign workers, students, and visitors are

not considered ‘landed’ and are classified separately from the aforementioned classes as ‘temporary

residents’ [4].

In Canada, permanent residents have full access to the same social services that Canadian citizens

are entitled to, including health care. In Ontario, residents have universal coverage under the

Ontario Health Insurance Plan (OHIP). Residents who move to Ontario must wait a three month

period after arrival prior to eligibility. OHIP coverage is maintained so long as residency is

maintained in Ontario for at least 153 days of every 12 month period [5].

Within Canada, Ontario is the destination for more than half of all new immigrants with 90% or

more settling in urban areas [6]. As of 2006, half of all Toronto residents were born outside of

Canada, with 81% being from a visible minority, and 66% of all births in Toronto being from

immigrant mothers. In Toronto, while 90% of newcomers (< 10 years in Canada) reported speaking

either some English or French, 47% of Toronto’s populations had a mother tongue other than

English or French (84% for newcomers). 5.3% of all Toronto immigrants had no knowledge of

English or French and this proportion was double among newcomers [6].

For pediatric immigrants and their families in Canada, pre- and post-migration life exposures may be

unique, and are not experienced by children born in Canada or by children whose parents are

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Canadian. While language remains one of the more easily measured differences in health systems

interactions in comparing Canadian born citizens with immigrants, other less quantifiable

distinctions exist. These include differences in culture, socioeconomic status, family structure and

supports, health status, acclimatization and acculturation. Additionally, the duration of residence in

Canada may predict health outcomes and health system interactions. Understanding these

differences that immigrants may experience through migration is important for understanding how

health behaviours are shaped. This will allow for more appropriately targeted strategies for health

service delivery. Moreover, traditional social determinants of health, such as socioeconomic status,

which have been well demonstrated to impact the use of the Canadian health system, may not

explain health system use by immigrants [7-11]. Immigrants are often highlighted in the literature

as being socially disadvantaged and in need of access to equitable healthcare, but there may be

under-recognized protective migrant factors that affect health system interactions that we need to

better appreciate [12-16].

In adults, there is a large body of literature describing the “healthy immigrant effect” or “healthy

immigrant paradox” whereby immigrants to Canada arrive in better health than their Canadian

equivalents despite facing a number of socio-demographic challenges [13, 17-19]. This is thought to

be related to self-selection of immigrants who may be healthier, able bodied and motivated to

obtain and maintain good health, as well as the screening process for immigrants that precludes

immigrants with serious health issues and favours educated, English or French-speaking, and skilled

applicants. The “convergence hypothesis” suggests that immigrants’ health over time converges

towards that of the host population [13, 14, 19, 20]. This is thought to be related to adoption of

unhealthy behaviours after migration, challenges in finding employment and financial stress, lack of

a social support network, and barriers to accessing health services especially for preventative

healthcare [6, 13, 14]. While these hypotheses may hold true from some immigrants, differences

may exist among sub-populations of immigrants - and to varying degrees. More importantly, there

is little data in pediatrics that supports the healthy immigrant effect or convergence hypothesis [21].

This void in the literature highlights the need for measuring health outcomes and health systems

interactions in this growing and vulnerable population.

One particular area that demands our attention and understanding is immigrant use of, access to,

and quality of care in the ED. The ED often serves as the first point of contact with the health

system for an ill child, and barriers in the ED relating to language or culture can be detrimental to a

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child’s health outcome. Correspondingly, identifying deficiencies in the provision of safe and quality

care through the use of internationally established ED outcome measures can serve to better

mitigate vulnerabilities faced by immigrants. One such established outcome measure is the

proportion of patients that visit an ED and return [22, 23]. Return visits may reflect both the quality

and safety of care provided but may also reflect underlying disease progression, especially in

children. In Ontario, children are among some of the highest users of EDs and more than one third

of children under five visit an ED annually [24]. Children present with a wide range of illnesses and

degrees of acuity. Thus, examining return visits to EDs by pediatric immigrants serves as an

opportunity to better understand health system interactions in this population.

1.3 The Cost and Burden of Emergency Department Revisits

A substantial proportion of all ED patients return to the ED after being seen and discharged. Revisits

may contribute to large, unnecessary costs to the health care system and to families. Understanding

why revisits occur, which patients may be at higher risk for revisits, how to prevent revisits, and how

revisits function as a proxy for measuring quality and safety of health care delivery are important for

policy makers, health care providers, and families.

Defining a return ED visit in the literature is variable, with some return visits being measured within

48 hours of an index visit and others measured up to 30 days of an index visit [25-32]. In defining

the time to revisit an ED, we must attempt to capture the same episode of illness without

erroneously including a new episode of illness. The majority of studies on ED revisits use 72 hours

[28, 33-36] as a time to revisit. In pediatric populations, most visits to the ED are related to

infections such as upper respiratory tract infections or gastroenteritis [33, 37, 38] and the typical

time course from illness onset to recovery is about a week. Thus, in these populations, seven days

may more appropriately capture ED revisits related to the same episode of illness.

In Canada, only three studies have been published on all-cause pediatric ED revisit rates. The

authors report approximately 4-5% of children who present to an ED and are discharged return

within 72 hours [27, 36, 39]. Similarly, in the US, the ED revisit rates for pediatrics are roughly 3.5-

4% [37, 40]. However, there is large variability, with revisits reported as low as 2.5% and as high as

16% [23, 37, 41]. Approximately 80% of revisits are unscheduled and the most common reasons for

visiting are for infectious diseases and asthma [36, 37].

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The risk of a return visit to the ED is dependent on a number of clinical and demographic factors.

Patients have a greater likelihood of revisiting if they are young (especially less than one year of

age), if they are sicker at their initial presentation (higher acuity triage score), if they have an

infection related complaint, or if the visit takes place during the winter months [33, 37, 42]. In

children with fever or infection-related complaints, the presence of chronic disease, acute triage

category, and Medicaid insurance were all identified as risk factors for return visits in an urban

single centre American study [40]. Race and socioeconomic status may also play a role in return

visits. In Dy et al.’s US study, children with fractures were found to be 27% more likely to return the

ED if they were non-white and 55% more likely to revisit for fractures if they had government

insurance as compared to those with private insurance [43]. Similarly, patients with asthma have

been shown to have higher revisits if they are non-white race [44]. Conversely, Cho et al. [33] did

not find any differences in return visits between races in a large US study using administrative data.

Unplanned ED revisits can be used as a measure of quality and safety of delivery of care. In Ontario,

evidence-based quality of care indicators for EDs were developed through a nationally

representative and scientifically rigorous process. Unplanned return visits leading to admission and

unplanned return visits without admission were among the top indicators identified to measure

quality of care in the ED [22]. ED revisits can be a reflection of potential medical management

errors, with the treating team’s failure to give a proper assessment, treatment, or follow up

instructions. Revisits may reflect unmet needs related to discharge education, including challenges

communicating effectively with a family and failure to understand instructions. Mahmoud et al.

evaluated satisfaction with service in the ED between English and non-English speaking adults [45].

They reported that patients experience the same friendliness but decreased promptness of service

in non-English speaking adults compared with those who spoke English. Similarly, Carrasquillo et al.

reported non-English speakers were less satisfied with their care in the ED, less willing to return to

the same ED if they had a problem they felt required emergency care, and reported more problems

with their care compared with English speakers. They identified the use of professional interpreters

and increasing language concordance between patients and providers as strategies to improve

satisfaction among non-English speakers [46]. Language barriers can increase the risks to patient

safety, leading to adverse events. Divi et al. demonstrated communication barriers played a role in

over 50% of adverse events in non-English speakers in several US hospitals [47].

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Return ED visits may also reflect another key issue within the health care system: the inappropriate

use and overuse of the ED. The ED may be, for example, where a patient or family goes for the

majority of their non-emergency care; they have limited or non-existent access to quality follow-up

care and consequently use the ED as a substitute. Revisits can also indicate dissatisfaction with the

care provided on the initial visit or desire for a second opinion. On the other hand, ED revisits may

reflect the natural history of the disease with patients’ symptoms persisting or deteriorating and

requiring further acute care assessment and management. Using a chart review, Depiero et al.

examined the association between subsequent admission to hospital and revisits to the ED following

an index visit. The authors reported 90% of initial ED evaluations were considered appropriate and

returns were primarily for progression of illness [34]. In adults, disease persistence or progression

accounted for 72% of return visits, with 14.5% found to have a missed or wrong diagnosis at the

initial visit [48].

1.4 Health Services Access, Use, and Safety for Immigrants.

Publicly funded health care has long been a value associated with Canadian national identity and

connected to Canadian national pride. Nonetheless, there are differences in healthcare utilization

and access between immigrant and Canadian born families. Canada’s healthcare system is

characterized by universal coverage, funded primarily though income taxes and delivered through

provincially coordinated health systems. Individuals with a health concern may therefore either

contact a primary care provider, urgent care centre, or ED to obtain advice or treatment, at no

personal cost. Despite this ‘universal’ health system in Canada, inequities in healthcare utilization

and delivery by and for immigrants may in part stem from differences in health, but may also reflect

differences in interactions with the healthcare system.

Access to primary care may be different for immigrants compared with Canadian-born families. This

may, in turn, account for disparities in ED use. In Toronto, analysis of data from the Canadian

Community Health Survey suggests that newcomers are less likely to report having a primary care

provider compared with Canadians (85.1% for newcomers versus 87.3% for Canadians). Conversely,

long term immigrants (>10 years in Canada) have higher proportions with a primary care provider

compared with non-immigrants (91.1% for long term immigrants) [6]. A similar pattern of primary

care access was found in an analysis of data from the 2006 Ontario Primary Care Access Survey, a

population based Ontario-wide telephone survey [49]. Together, these data suggest recency of

immigration plays a potentially important role in health system use and interactions. As a result of

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this reported reduced access to a primary care provider, newcomers may more often use walk-in-

clinics, urgent care centres, or EDs for their care. Aside from being potentially more costly to the

health care system, this may lead to more fragmented and poor quality care.

Currently, little high quality data has been published on Canadian ED use by immigrants. One older

study in Ontario adults evaluated the accessibility of health care services by immigrants using the

1990 Ontario Health Survey. This study suggested that general practitioner use was slightly higher

in immigrants and the rates of ED visits was often lower compared with Canadians after controlling

for self-reported health status and age [50]. This study was limited by the innate bias in such survey

studies. More importantly, over the last 25 years, there have been a number of changes to delivery

of primary care that would not be reflected in their data. Data from the Primary Care Access Survey

in 2008 suggests that ED use in adults was 43% higher in recent immigrants and 30% higher in non-

immigrants compared with longer-term immigrants (> 10 years since arrival) [49]. These data are all

based on surveys in adults precluding interpretation to pediatric populations. Notably, these

surveys were administered in English and French which may bias results with immigrants with

limited Canadian language proficiency.

Though little Canadian data on ED use by immigrants exists, understanding health service delivery

patterns in American EDs and those around the globe may help us to identify deficiencies in our own

system. In the US, data from adults shows lower use of ED services in non-citizens compared with

naturalized and US-born Americans [51]. The ED use was only partially explained by healthcare

need and insurance. In pediatric populations in the US, Vaughn and Jacques reported an increased

risk of pediatric ED use by Latino children with lower levels of acculturation compared with those

with higher levels of acculturation. The medical reasons for the ED visits were not different

between groups suggesting differences in newcomer Latino’s access to care and use of the health

system compared to those who are more acculturated [52]. In Israel, Davidovitch et al. reported

lower use of EDs and hospitalizations for immigrants in Israel using health administrative data.

These patterns of health system use did not change even after 10 years of having immigrated to

Israel suggesting economic and cultural factors, rather than duration of residence, may influence

health care utilization [53]. In Denmark, variability in ED utilization exists depending on region of

origin with lower utilization rates among European, Western and some non-Western immigrants

compared with native Danes [54].

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Barriers to care including cultural competency among health service providers may, in part, explain

some of the observed variability in the literature with respect to ED use. Discrimination and racism

may lead to guardedness and distrust with health system use, discouraging immigrants from seeking

healthcare. Similarly, variability in cultural congruence, such as understanding or interpretation of

expressions of distress may be a barrier to optimal care for immigrants. Adult newcomers in

Toronto report feeling rushed in medical appointments, feeling inadequate explanations about

medical procedures, and experience a lack of empathy from health care practitioners about their

immigration challenges and experiences [6]. Cultural competency may affect decision making by

care providers in the ED during assessment and management of a patient. Payne et al. [55] using a

retrospective case-cohort design evaluated the association of race and language on laboratory and

radiologic testing in the pediatric ED. They reported African American and bi-racial patients had

decreased odds of laboratory testing compared with non-Hispanic whites. Native American, African

American, biracial, and Hispanic patients had lower odds of radiological testing compared with non-

Hispanic whites. Subgroup analysis stratifying by reason for visit showed that visits for children with

infectious symptoms such as fever or upper respiratory tract symptoms, where there are fewer

treatment protocols, confirmed differences between races. In patients with head injury, where

more standardized approaches exist, there was no association between race and laboratory or

radiological testing. These data highlight the value of standardization of care algorithms as a

potential strategy for reducing variability in care between racialized groups.

Language has been well documented to contribute to variability in access to care and quality of care

by patients. Engendering empathy, participation in decision making, and reception of sufficient

information about a health issue are less likely when language barriers exist [56]. Adult Spanish

speaking patients in the US have been shown to have poorer health literacy and adherence to

discharge instructions compared with English speakers [57]. In their matched cohort design, Smith

et al. reported only 78% of Spanish speakers compared with 94% of English speakers understood

discharge instructions and 43% of Spanish and 83% of English speakers kept their follow up

appointment. Formal tests of health literacy were also significantly lower in Spanish speakers and

those with poor functional health literacy were less likely to adhere to discharge instructions. This

study highlighted that both language and health literacy are important for health quality and safety

upon discharge from the ED.

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Language barriers in pediatric EDs in the US have been shown to contribute to significantly higher

charges for services and tests compared with other patients with similar presenting complaints.

Language barriers also contribute to longer length of stay in the ED in non-English speakers

compared with English speakers, after controlling for a number of clinical and demographic variables

[58]. Language barriers can contribute to ED return visits leading to admission to hospital.

Gallagher et al. [29] measured 72 hour return visits to a pediatric ED in a single centre study. They

reported patients with limited-English proficiency were more likely to have a lower acuity score, and

have a revisit the ED leading to admission compared with English speakers. Use of interpreter

services may mitigate some of the communication challenges faced by new immigrants.

Interpreters have been shown to reduce medical error and improve communication with the care

team [59].

In summary, Canada has a large and continually growing pediatric immigrant population. There is

potential for disparities to exist in delivery of quality and timely care for immigrants across North

America, especially for those not proficient in the English or French. The ED may be a place where

suboptimal care is delivered depending on immigrant status resulting in increased emotional, time,

and financial costs to families and the health care system. There is currently limited quality data on

the influence of immigrant status on pediatric ED use and outcomes in Canada. Assessing revisits in

this population will help to identify barriers to accessible and quality care that may be experienced

by immigrants and inform ED care providers and policy makers. This information can be used to

change practice for delivery care to immigrants by providing culturally sensitive, language

appropriate information during a visit and upon discharge. It can be used to target educational and

structural interventions for ED care providers to ensure these potentially higher risk individuals are

being appropriately treated.

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2.0 Thesis Objectives and Hypotheses

2.1 Rationale and Relevance

Given the lack of information on pediatric immigrant health services interactions, we must develop a

better understanding of patterns of ED use in this population. This will allow us to identify barriers

to accessible and quality care experienced by immigrants. In particular, this information will enable

us to address these barriers and target strategies to reduce unnecessary emergency revisits and

improve quality of care. Results of this study have the potential to impact policy on the delivery of

care to pediatric immigrants and alter the way health care providers approach immigrant patients

for assessment and treatment.

2.2 Research Questions

Primary

Does being a child living in urban Ontario from an immigrant family increase the risk of making an

unscheduled revisit to the ED compared with children from non-immigrant families?

Secondary

Do certain sub-groups of immigrants living in urban Ontario, where language or culture may act as a

barrier to care, have an increased risk of unscheduled return visits to the ED?

Do pediatric immigrants and certain subgroups within pediatric immigrants living in urban Ontario

have worse revisit outcomes on the return visit to an ED compared with non-immigrants living in

urban Ontario?

2.3 Specific Objectives and Hypotheses

Primary

To test whether being a pediatric immigrant or a child born in Canada to an immigrant mother

increase the risk of making an unscheduled revisit to the ED within seven days of an initial visit (“7-

day revisit”) compared with non-immigrant children and children born to non-immigrant mothers

living in Census Metropolitan Areas of Ontario. We hypothesize that being an immigrant increases

the odds of 7-day ED revisits, especially in those who have more recently immigrated.

11

Secondary

To test whether being from certain subgroups of immigrants increases the risk of 7-day ED revisits

compared with other immigrant classes. These subgroups include refugees, families where English

or French is not the reported native tongue upon landing in Canada, families from countries where

the official language is not English or French, and region of origin (birth) based on the world regions

using UNICEF classification. We hypothesize that vulnerable immigrants groups including refugees,

patients from non-industrialized regions, and those without English or French as the native tongue

or official language of country of birth have a greater odds of a 7-day ED revisit.

To test whether pediatric immigrants have worse revisit outcomes compared with non-immigrants

as defined by revisits leading to a hospital admission or a worse Canadian Triage and Acuity Scale

score on the revisit. We hypothesize that immigrants have worse outcomes at their ED revisit.

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3.0 Methods

3.1 Overview of Methods

This was a retrospective population-based cohort study of immigrant and non-immigrant children

from birth to 17 years, living in Census Metropolitan Areas (CMA’s) of Ontario, who visited an

Emergency Department between April 1st, 2003 and March 1st, 2010. Health administrative and

demographic databases available at the Institute for Clinical Evaluative Sciences (ICES) were linked

to assess whether children revisited the Emergency Department within 7 days of their index visit.

3.2 Research Ethics Approval

Research ethics board approval was obtained from The Hospital for Sick Children, Sunnybrook

Health Sciences Centre, and The University of Toronto.

3.3 Data Sources

ICES is an independent, non-profit organization, dedicated to conducting research that contributes

to the effectiveness, quality, and efficiency of health care and health services in Ontario. ICES is

funded by the Ontario Ministry of Health and Long-Term Care (MOHLTC) and, as a prescribed entity

under the Personal Health Information Protection Act (PHIPA), houses extensive databases on

demographic and health services for people living in Ontario. ICES is responsible for possession,

custody, confidentiality, and security of all data. Patient records from a number of health and

demographic databases are linked through individual scrambled personal health identification

numbers, known as an ICES Key Number (IKN) [60].

National Ambulatory Care Reporting System (NACRS)

NACRS is one of the largest databases recording patient activities in Canada. NACRS provides

standard data collection and reporting tools used to capture all ambulatory care visits including day

surgery, outpatient clinics, and EDs. Data has been collected and reported since 2001. For ED data,

EDs across Ontario are required to report on a number of data elements [61]. Re-abstraction has

shown that over 98% of the data is accurately abstracted for the mandatory data elements used in

the current study. The only optional element used in this study is whether a visit was

scheduled/unscheduled and this has shown 87% accuracy in re-abstraction [62].

MOMBABY Database

13

This database, created at ICES, pairs all mothers with their newborn delivered in Ontario. It links the

Canadian Institute for Health Information Discharge Abstract Database inpatient admission records

of delivering mothers and their newborns. Prior to 2002, linkage was done probabilistically through

dates and diagnoses, and since 2002, there is a linking identifier. Through linkage with their IKN, the

MOMBABY database was used to identify newborns born in Canada to immigrant mothers. The

MOMBABY Database has been validated through ICES with a sensitivity of 96.1% and a specificity of

99.2% for determining mom-baby pairs [63].

Permanent Resident Data System (previously the Landed Immigrant Data System)

This federal database, maintained by Citizenship and Immigration Canada, holds socio-demographic

and immigration information on all permanent residents landing in Ontario from January 1st, 1985 to

the present. Information is collected from official immigration documents, last updated at the port

of entry on the date of landing. These records were linked deterministically and probabilistically to

the registry of the Registered Persons Database to obtain an IKN. The IKN was then used to link data

with OHIP numbers, which provides universal access to physician and hospital services except for

those residing in Ontario for less than three months and asylum seekers. Linkage evaluation to the

Registered Persons Database (RPDB) from 1985-2010 demonstrated approximately 86% matching

[64]. Since inception, linkage has improved over time and preliminary unpublished validation

studies demonstrate heterogeneity in linkage based on sub-region of origin and immigrant class

with East Asian and Economic class immigrants having the lowest proportion (77%) of linked

patients (personal communication).

2006 Canadian Census and Registered Persons Database

The Census provides statistical data on people living in Canada including household income data

within a dissemination area and divides the population into 15 Ontario Census Metropolitan Areas

(CMA’s) (see Appendix A for CMA’s). CMA’s are defined as areas consisting of one or more

neighbouring municipalities situated around a core. A CMA must have a total population of at least

100000 of which 50000 or more live in the core. Just over 70% of the Ontario population in 2006

lived in a CMA [65]. Neighbourhood characteristics are available through the Census using a postal

code conversion file. The Census was linked to the Registered Persons Database (RPDB) (using the

IKN) for the postal code for each patient to ascertain household income and deprivation index

quintiles within a dissemination area.

14

3.4 Study Population

The cohort included all children aged 0 to 17 years old living in CMA’s of Ontario with a valid OHIP

card who had a visit to an Ontario ED between April 1st 2003 and March 1st 2010 (to include 7 years

of study with a one year look back and seven day follow up period).

Children were excluded if they did not have a valid OHIP number (including those waiting the three

month residency waiting period, those with Interim Federal Health, and those from another

province using the Ontario health system). Exclusions also included visits to urgent care centres or

mental health facilities. Children were excluded if landed immigrant dates were not available, if no

disposition data was available (discharged, admitted, surgery, etc.) at the index visit, if they left

without being seen, and if they were not discharged home from the Emergency Department on the

index visit. Visits from patients who had an ED visit in the 30 days preceding the index visit were

excluded. Any visit after 30 days from a previous visit was considered a new episode of illness and

therefore included in the cohort as an index visit. If patients were transferred from another facility,

the index visit to be analyzed was that according to the primary facility.

Immigrants were defined as any child who is a landed immigrant (Economic class, Family class, or

Refugee class) arriving in Canada after January 1st, 1985 or the mother is a landed immigrant

(Economic class, Family class, or Refugee class) arriving in Canada after January 1st, 1985 and the

child has an Emergency Department visit to any Ontario hospital leading to a discharge. If the

landed immigration date and/or country of origin and birth of the mother and child were different,

the immigration information of the child was used.

3.5 Outcome Variables

Primary Outcome

The primary outcome was a revisit to the ED within seven days of an initial visit (7-day ED revisit). A

revisit was defined as any unplanned visit to an ED in Ontario (either the same one or a different ED

within Ontario) within seven days of the initial (index) visit. Seven days was chosen to capture

revisits made related to the index visit while avoiding visits made for new episodes of illness. ED

revisits rates in pediatrics have been reported at 3 – 5% for 72-hour revisits [36, 37, 39] and 6 – 11%

for 30-day revisits [66]. Zimmerman et al. have shown that using 14 days instead of 72 hours almost

doubles the rate of return visits for related illness [67]. Similarly, the Canadian Institute for Health

15

Information has shown return visits are 10 times higher when using 30 days instead of 1 day for

calculating a return visit to the ED [68]. ED revisits (leading to discharge and admission to hospital)

have been identified in Canada as a key performance measure in the delivery of safe and quality ED

care [22]. Ascertainment of an index visit and revisit data was done using data elements from

NACRS including the ED visit date (index and revisit), main reason for visit, Canadian Triage and

Acuity Scale score (CTAS score), visit disposition, patient demographics at the time of visit (age on

date of index visit, sex, postal code at time of visit), hospital, and whether the visit was scheduled or

unscheduled.

Secondary Outcomes

Secondary outcome measures were 1) admissions to hospital or death on the revisit and 2) a worse

CTAS score at the revisit compared with the index visit. While both of these measure may simply be

a reflection of disease progression, both measures may indicate worse outcomes for patients, and

both may indicate a failure by the initial ED team to appropriately assess, treat, or communicate

discharge instructions to a family.

3.6 Independent Variables

Main Exposure

The main exposure was maternal or child immigrant status accounting for exposure to a Canadian

setting by duration of residence in Canada and landed immigrant status. This was defined as the

time, in years, from landing in Canada to the Emergency Department visit. This variable was

modeled categorically with three groups, including non-immigrant, longer-term immigrant (>5 years

in Canada), and recent immigrant (≤ 5 years in Canada).

Subgroup Exposures For Within Immigrant Group

The immigrant group was further subdivided by visa class: Refugee, Family class, or Economic class.

Exposures for the immigrant subgroup also included native tongue declared upon landing (English,

French, or neither English/French), official language of country of birth (English, French, or neither

English/French), and world region of origin (ascertained from country of birth, categorical), based on

UNICEF’s world regions [69] (See Appendix B for a list of countries and classification by UNICEF

world region). All data elements used in the immigrant groups are mandatory to report and based

on official immigration documentation. Only native tongue is self-reported at the time of landing.

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3.7 Covariates

Age and Sex

As potential confounders, we considered patient sex and age at the time of the index presentation.

Age was divided categorically based on clinically and physiologically relevant differences in age

groupings that may lead to illness and an ED visit (birth to less than 12 months, 1 to 2 years, 3 to 6

years, 7 to 10 years, 11 to 14 years, and 15 to 17 years). Younger children are at an increased risk of

having a higher severity of illness on presentation, greater likelihood of being brought to an ED, or

revisiting an ED [27, 33, 41, 44].

Socioeconomic Status

Disparities in health and health care use have been well documented to be associated with

socioeconomic status. For example, children in Ontario with pneumonia or asthma have a higher

risk of admission to hospital if they are in the lowest versus the highest income quintile [7]. Each

patient in the current study was assigned a material deprivation quintile from the Ontario

Marginalization Index based on their place of residence at the time of the index visit. The Ontario

Marginalization Index (OMI) is a census and geographically based index used for planning,

assessment, resource allocation, monitoring of inequities, and research. It is used to explore

multiple dimensions of marginalization in urban and rural Ontario. The index is made up of four

dimensions including residential instability, material deprivation, ethnic concentration, and

dependency at the dissemination area (DA) level and has been demonstrated to be stable across

time periods and across different geographic areas [70]. DAs consist of small populations (400 to

700 people) and are relatively homogeneous [71]. For this study, the material deprivation index

within a DA was used as a proxy for socioeconomic status. Indicators measured within this

dimension include: proportion of the population aged 25+ without a certificate, diploma, or a

degree, proportion of families who are lone parent families, proportion of the population receiving

government transfer payments, proportion of the population aged ≥ 15 who are unemployed,

proportion of the population living below the low income cut off, and proportion of households

living in dwellings that are in need of major repair [70].

Neighbourhood income quintile using the 2006 Canadian Census data was also used as a measure of

socioeconomic status. Neighbourhood income quintile was approximated using the postal code

from the NACRS record of each child at each visit, linked to the income quintile within the DA. The

17

quintiles were divided from Q1 (lowest income group) to Q5 (highest income group) and were

adjusted for household and community size.

Propensity to Use an ED

The number of ED visits in the preceding year for each patient was used to describe the propensity

to use the ED as a source of health care (0 visits, 1, visit, 2 visits, and 3 or more visits). Children who

use the ED more frequently for care may have greater health care needs or comorbidities. Similarly,

the number of low acuity visits (CTAS 4 and 5) in the year preceding the index visit was used to

measure the propensity of a family to use the ED for non-urgent health needs and may be a

reflection of access to primary care for the child. Children with poor access to primary care may visit

and revisit an ED more frequently compared with their counterparts with no accessibility issues.

Acuity of Illness

Another potential confounder was the CTAS score. This score is used to account for severity and

acuity of illness on presentation to the ED. It is mandatory for all EDs to assign a score to a patient

at the time of triage. It factors in the patient’s reason for visit, vital signs, pain score, as well as

underlying comorbidities that may affect the urgency with which they need to be assessed and

treated. CTAS scores are rank ordered from one to five with one being the most emergent.

Timing of Visit

For children visiting the ED during busy hours (e.g. during the evening) or during a time when few

other options for care exist (e.g. the weekend or holidays), the interaction with the health system

and ED provider may be different and affect outcome. Shift time has been shown to affect quality of

care, including rates of return visits [29, 36]. Delivery of appropriately detailed patient assessments

and discharge instructions may be hindered during a busy ED shift, ultimately leading to worse

outcomes. Thus, shift time (day (8:01 – 16:00), evening (16:01 – 24:00), night (00:01 – 8:00)) and

shift day (weekend, weekday/holiday) were accounted for in the analysis. Holidays included all

statutory holidays as set out by the Ontario Ministry of Labour.

Hospital Factors

Annual hospital pediatric ED volume was also considered and included as a covariate. ED’s that

experience high volumes of children may differ in the quality of interaction with the patient due to

18

more experience with pediatric illness management. This may, in turn, lead to reduced revisits to

the ED. Hospital size has been shown to be associated with rates of ED return visits, with smaller

hospitals having almost double the return visit rate compared with larger ones [68]. For the current

study, the annual hospital pediatric ED volume was accounted for and measured in tertiles (low,

medium, and high volume centres).

A final potential confounder is the hospital type for the ED visit. Pediatric hospitals may have lower

revisit rates because of more experience in diagnosing, managing, and arranging follow-up for

pediatric patients. Pediatric hospitals are centred in major urban centres (Toronto, Ottawa, and

London), where a greater proportion of immigrants settle [4]. Therefore, immigrants may appear to

have lower revisit rates if a greater proportion is seen in these pediatric centres, compared to

community hospitals without a pediatrician available. For the current study, hospital type was

defined based on physician staffing in the ED. These categories included “Pediatric” hospitals where

trained pediatric emergency physicians or pediatricians were the main front line staff, “Teaching”

hospitals where staff were affiliated with health sciences schools and provide complex patient care

but are not dedicated pediatric hospitals, “Community with Pediatrics” where the ED was staffed by

community physicians with a consultant pediatrician available to the ED, and “Small” where the ED

was staffed by physicians without pediatric consultation available.

3.8 Statistical Analysis

All statistical modeling was carried out using SAS for UNIX version 9.3 (SAS Institute, Cary, NC).

Statistical significance was defined as two-tailed p < 0.05.

All outcomes and covariates were categorical variables, observed as numbers and proportions. The

Chi-square test was used to assess for differences between groups. Because of a very large sample

size, equivalence testing for baseline demographic and visit characteristics was also used to assess

for differences with a +/- 5% difference considered significant [72]. Subsequently, odds ratios (OR’s)

with 95% confidence intervals (CI) and p-values were calculated using logistic regression models to

further examine the relationships between the outcomes and the independent variables.

Multi-collinearity

Multi-collinearity for the independent variables was tested for each outcome by evaluating the

variance inflation factors (VIF) and tolerances. Values of approximately 0.4 or less for the tolerance

19

and approximately 2.5 or greater for the VIF were considered correlated [73]. Where multi-

collinearity occurred, the more clinically important variable based on the literature and clinical

relevance was kept in the model.

Modelling Strategy

Prior to running logistic regression models, log binomial regression modeling was considered as a

modeling strategy to obtain relative risks for the various outcomes. Using this strategy, models

repeatedly failed to converge and therefore log binomial models could not be used. Subsequently, a

modified Poisson regression model was also considered. Unfortunately, due to the large sample size

and complexity of modelling, there was insufficient computer memory to run these models. Thus,

logistic regression models were chosen for modelling the outcomes. Based on a review of the

literature, the main outcome measures were expected to be relatively rare (< 10%). Therefore, the

impact of the overestimation of the relative risk using logistic regression models was expected to be

minimal.

In considering statistical modelling, multiple index ED visits by the same patient over the study

period were analyzed as separate visits. Thus clustering within each patient required consideration.

In the models however, adjustment was made for most variables at each visit that were unique to

each visit. For example, almost all patient level covariates (except sex) were unique to each visit, as

were visit (e.g. reason for visit, visit time or day) and hospital characteristics. Variables that may

have been affected by clustering within a patient on repeated measures include sex and some

immigration characteristics (native tongue, language of country of birth, and region of origin), as

well as some unmeasured within patient variables. Thus models were evaluated with both logistic

regression modelling alone, in addition to logistic regression modelling with generalized estimating

equations (GEE) to account for repeated observations within a given patient. For these GEE models,

an exchangeable correlation structure was chosen as this correlation matrix is most often used for

health data where there is no time dependence in the repeated measure [74]. For the models using

GEE, there was insufficient memory with the computer programming to run the full models and

therefore we used 5 samples of 30% of the population and pooled the estimates and standard

errors. Where there were no differences in the beta-estimates and standard errors using +/- 10%

change in the estimates as well as p-values, the logistic regression models without GEE were

reported. Because data was from administrative sources and almost all data elements were

20

mandatory to report, the proportion of missing data was expected to be low (< 5%). To account for

missing data, complete case analysis was used in the regression analyses.

For each model, variables were selected a priori that were felt to be clinically significant as reported

in the literature. These variables were kept in the final model, regardless of clinical significance.

Only highly correlated variables based on the aforementioned testing were removed from the final

model. No interaction terms were tested as we had no pre-determined hypotheses with respect to

interactions. The relationship between the independent variables (immigration status, immigration

class, native tongue, language of country of birth, and region of origin) were expressed as adjusted

odds ratios with 95% confidence intervals and associated p-values.

21

4.0 Results

4.1 Children living in a Census Metropolitan Area visiting an Ontario ED 2003-2010

The initial cohort and flow chart of exclusions are shown in Figure IC (Appendix C). There were

6828208 ED visits for children from birth to 17-years old for children living in Ontario between April

1st, 2003 and March 1st, 2010. After excluding 2641761 visits by children who did not live in a CMA,

390805 visits by children who visited an urgent care centre or mental health facility, and 472741

visits where a patient had a visit within the preceding 30 days, there were 3322901 visits (from

1555314 unique patients) that remained. Most patients visited the ED only once during the study

period (range 1 – 35 visits) though there were 253 patients with 20 or more visits and 12753

patients with 10 to 19 visits during the study period.

4.2 Overall composition of population based on immigrant status

Of the initial 3322901 visits, 2813382 (84.7%) were by non-immigrants, 341621 (10.3%) were by

longer-term immigrants and 167898 (5.0%) were by recent immigrants. For the immigrant groups

(both longer-term and recent immigrants), data from mom-baby pairs (i.e. immigration information

was based on maternal immigrant status) comprised 352705 (69.2%) of the total immigrant

population with 156814 (30.8%) of the immigrant visits being from data from children who were

born outside of Canada and immigrated to Canada.

4.3 Baseline characteristics of cohort who visited an ED

The baseline patient characteristics of patients who visited and ED from April 1st, 2003 to March 1st

2010 are provided in Table 1 overall and divided by immigration status. The largest proportion of ED

visits was by infants less than one year old with a significantly higher proportion of infants visiting

the ED in the recent immigrant group (35.5% vs. 21.0% (longer-term immigrant) and 20.1% (non-

immigrant)) compared with other groups. 55.4% of visits were by males but there were no

differences by income quintile. However, recent immigrants visiting EDs were more likely to be

from the lowest income quintile (41.8%) compared with longer-term immigrants (29.4%) and non-

immigrants (18.9%). Approximately one third of patients had had at least one previous ED visit in

the year preceding their index visit. Non-immigrants had the highest proportion (40.3%) with at

least one previous visit in the preceding year. 77.8% of patients had no low-acuity visit in the

22

preceding year, though the subgroup of non-immigrants had more low acuity visits (23.2%)

compared with longer-term (17.1%) and recent (15.8%) immigrants.

Approximately 45.7% of visits were non-urgent based on a CTAS score of 4 or 5 with non-immigrants

having the highest proportion of low acuity visits (46.3%). The majority of visits (40.2%) were for

injury or trauma with a significantly higher proportion of non-immigrants having injury or trauma as

their reason for the visit (41.2% vs. 35.9% (longer-term immigrants) and 32.6% (recent immigrants)).

Approximately half of all visits took place in the evening and one third of visits took place on

weekends or holidays. Recent immigrants had the highest proportion of visits to an emergency

department in a pediatric hospital (21.9%).

23

Table 1. Baseline characteristics of pediatric patients from CMA’s in Ontario who visited an ED from April 2003 to March 2010

Patient Characteristics

Non-immigrant n = 2813382

Longer-term immigrant n = 341621

Recent immigrant n = 167898

Total N = 3322901

p-value*

p-value†

Age (years), n (%) 0 - <1 564133 (20.1) 71598 (21.0) 59687 (35.5) 695418 (20.9) <.001 1.000 1 - 2 221781 (7.9) 29872 (8.7) 17555 (10.5) 269208 (8.1) 3 - 6 592129 (21.0) 87612 (25.6) 33448 (19.9) 713189 (21.5) 7 -10 435292 (15.5) 57585 (16.9) 21440 (12.8) 514317 (15.5) 11 - 14 519109 (18.5) 52510 (15.4) 19697 (11.7) 591316 (17.8) 15 - 17 480938 (17.1) 42444 (12.4) 16071 (9.6) 539453 (16.2)

Sex, n (%) Female 1265033 (45.0) 144622 (42.3) 71502 (42.6) 1481157 (44.6) <.001 <.001 Male 1548349 (55.0) 196999 (57.7) 96396 (57.4) 1841744 (55.4)

Neighbourhood income quintile, n (%) Missing 9526 (0.3) 360 (0.1) 285 (0.2) 10171 (0.3) <.001 1.000 1 (lowest) 531450 (18.9) 100318 (29.4) 70216 (41.8) 701984 (21.1) 2 535892 (19.0) 75442 (22.1) 36212 (21.6) 647546 (19.5) 3 563960 (20.0) 68985 (20.2) 25905 (15.4) 658850 (19.8) 4 608918 (21.6) 59246 (17.3) 21382 (12.7) 689546 (20.8) 5 (highest) 563636 (20.0) 37270 (10.9) 13898 (8.3) 614804 (18.5)

Deprivation index, n (%) Missing 127391 (4.5) 11457 (3.3) 7299 (4.3) 146147 (4.4) 1 (least deprived) 782270 (27.8) 76610 (22.4) 27448 (16.3) 886328 (26.7) <.001 1.000 2 592109 (21.0) 61020 (17.9) 23696 (14.1) 676825 (20.4) 3 483978 (17.2) 61330 (18.0) 30477 (18.2) 575785 (17.3) 4 392088 (13.9) 56883 (16.1) 35261 (21.0) 484232 (14.6) 5 (most deprived) 435546 (15.5) 74321 (21.8) 43717 (26.0) 553584 (16.7)

ED visits in previous year, n (%) 0 1680687 (59.7) 224442 (65.7) 113589 (67.7) 2018718 (60.8) <.001 <.001 1 622266 (22.1) 68700 (20.1) 31843 (19.0) 722809 (21.8) 2 259480 (9.2) 26122 (7.6) 12164 (7.2) 297766 (9.0) 3+ 250949 (8.9) 22357 (6.5) 10302 (6.1) 283608 (8.5)

Low acuity visits in previous year, n (%) 0 2161830 (76.8) 283336 (82.9) 1414164 (84.2) 2586582 (77.8) <.001 1.000 1 455022 (16.2) 44400 (13.0) 199973 (11.9) 519395 (15.6) 2 124514 (4.4) 9833 (2.9) 4557 (2.7) 138904 (4.2) 3+ 72016 (2.6) 4052 (1.2) 1952 (1.2) 78020 (2.4)

Index ED visit characteristics

CTAS, n (%) 1-2 (Resus.) 278198 (9.9) 37627 (11.0) 19603 (11.7) 335428 (10.1) <.001 0.142 3 (Emergent) 1231577 (43.8) 158765 (46.5) 78716 (46.9) 1469058 (44.2) 4-5 (Non-urgent) 1303218 (46.3) 145193 (42.5) 69562 (41.4) 1517973 (45.7)

Chief complaint index visit, n (%) Injury/trauma 1158436 (41.2) 122785 (35.9) 54760 (32.6) 1335981 (40.2) <.001 1.000 Neurologic 67203 (2.4) 9274 (2.7) 4217 (2.5) 80694 (2.4) Skin problems 102702 (3.7) 12109 (3.5) 5973 (3.6) 120784 (3.6) Administrative 54317 (1.9) 5379 (1.6) 3758 (2.2) 63454 (1.9) Gen. symptoms 49339 (1.8) 6781 (2.0) 4067 (2.4) 60187 (1.8) Other 241447 (8.6) 29337 (8.6) 14172 (8.4) 284956 (8.6) Mental health 45783 (1.6) 3706 (1.1) 1219 (0.7) 50708 (1.5)

24

Newborn 18700 (0.7) 2747 (0.8) 3080 (1.8) 24527 (0.7) Infections 161920 (5.8) 27681 (8.1) 15001 (8.9) 204602 (6.2) Cancer 3913 (0.1) 707 (0.2) 390 (0.2) 5010 (0.2) Gastrointestinal 181086 (6.4) 29286 (8.6) 14923 (8.9) 225295 (6.8) Asthma 100325 (3.6) 14076 (4.1) 4512 (2.7) 118913 (3.6) URTI/Otitis media 561775 (20.0) 65963 (19.3) 34385 (20.5) 662123 (19.9) Fever 66436 (2.4) 11790 (3.5) 7441 (4.4) 85667 (2.6)

Shift time, n (%) Night 355752 (12.6) 53543 (15.7) 26770 (15.9) 436065 (13.1) <.001 0.050 Day 1025044 (36.4) 117058 (34.3) 58120 (34.6) 1200222 (36.1) Evening 1432586 (50.9) 171020 (50.1) 83008 (49.4) 1686614 (50.8)

Shift day, n (%) Weekday 1820402 (64.7) 218985 (64.1) 106249 (63.3) 2145636 (64.6) <.001 <.001 Weekend/holiday 992980 (35.3) 122636 (35.9) 61649 (36.7) 1177265 (35.4)

Hospital type, n (%) Community 1957842 (69.6) 251889 (73.7) 119389 (71.1) 2329120 (70.1) <.001 1.000 Pediatric 475906 (16.9) 70278 (20.6) 36726 (21.9) 582910 (17.5) Small 89835 (3.2) 1771 (0.5) 464 (0.3) 92070 (2.8) Teaching 289799 (10.3) 17683 (5.2) 11319 (6.7) 318801 (9.6)

Annual hospital pediatric ED volume, n (%)

High (> 16000) 982801 (34.9) 118103 (34.6) 56675 (33.8) 1157579 (34.8) <.001 1.000 Low (< 10000) 988368 (35.1) 76925 (22.5) 38293 (22.8) 1103586 (33.2) Medium (10000 -

16000) 842213 (29.9) 146593 (42.9) 72930 (43.4) 1061736 (32.0)

* = Chi-squared test

† = Equivalence test of proportions. Values greater > 0.05 indicate non-equivalence.

Table 2 demonstrates the baseline characteristics of immigrants visiting an ED by immigration

characteristics. Economic immigrants made up 38.2% of all immigrants who visited an ED during the

study period and 19.9% were refugees. 15.8% of immigrants had English as their native tongue and

0.5% of immigrants had French as their native tongue. 83.7% of immigrants were born in or to

mothers from countries where English or French are not official languages. The most common

regions of origin were South and East Asia. Among recent immigrants there was a higher proportion

from South Asia and smaller proportions from industrialized nations and Latin America and the

Caribbean compared with longer-term immigrants.

Table 2. Baseline immigration characteristics of pediatric immigrants from CMA’s in Ontario who visited an ED from April 2003 to March 2010

Immigration characteristics Longer-term immigrants n = 341621

Recent immigrants n = 167898

Total n = 509519

p-value*

p-value†

Immigration Category, n (%) Economic 121955 (35.7) 72637 (43.3) 194592 (38.2) <.001 1.000 Family 158444 (46.4) 55192 (32.9) 213636 (41.9) Refugee 61222 (17.9) 40068 (23.9) 101290 (19.9)

25

Native tongue, n (%) English 62422 (18.3) 17984 (10.7) 80406 (15.8) <.001 1.000 French 1359 (0.4) 1398 (0.8) 2757 (0.5) No English or French 277840 (81.3) 148516 (88.5) 426356 (83.7)

Country with official language, n (%) English 55940 (16.4) 17600 (10.5) 73540 (14.4) <.001 1.000 French 5128 (1.5) 4579 (2.7) 9707 (1.9) No English or French 280553 (82.1) 145719 (86.8) 426272 (83.7)

Region of origin, n (%) Central and Eastern Europe 28201 (8.3) 14423 (8.6) 42624 (8.4) <.001 1.000 East Asia 65166 (19.1) 30534 (18.2) 95700 (18.8) Eastern and Southern Africa 20253 (5.9) 10458 (6.2) 30711 (6.0) Industrialized 51220 (15.0) 20785 (12.4) 72005 (14.1) Latin American and Caribbean 65493 (19.2) 21399 (12.7) 86892 (17.1) Middle East and North Africa 29906 (8.8) 19914 (11.9) 49820 (9.8) South Asia 75390 (22.1) 46237 (27.5) 121627 (23.9) West and Central Africa 5992 (1.8) 4148 (2.5) 10140 (2.0) * = Chi-squared test

†= Equivalence test of proportions. Values greater > 0.05 indicate non-equivalence.

4.4 Overall outcomes: revisits, revisits leading to admission, revisits with a worse CTAS score

Figure IIC depicts the exclusions for the revisits (Appendix C). There were 295457 ED revisits within

7 days of an index ED visit. After exclusions, 249648 7-day ED revisits remained as the main

outcome.

The overall unadjusted outcomes are shown in Table 3. Of the 3322901 ED visits from April 2003 to

March 2010 that led to discharge from the ED, 249648 (7.5%) resulted in a revisit within 7 days. Of

those that revisited the ED, 31803 (12.7%) resulted in an admission to hospital (1.0% of all index

visits led to admission on the revisit). For all revisits, 46464 (18.6%) resulted in a worse CTAS score

at the revisit as compared to the index visit.

Table 3. Revisit Characteristics

Outcome (n = relevant denominator) Total, n (%)

Revisits (n = 3322901) 249648 (7.5) Revisit leading to admission (n = 249606)* 31803 (12.7) Revisit leading to worse CTAS score (n = 249648 ) 46464 (18.6) *42 revisit disposition observations on the revisit were missing

26

4.5 Primary outcome: ED revisits

4.5.1 Association of immigrant status with ED revisits

The ED revisits by immigrant status and by patient and hospital characteristics are shown in Table 4.

Overall, recent immigrants had the highest proportion of revisits to an ED within 7 days of an index

visit (8.0% versus 7.5% for longer-term and non-immigrants). Revisits were more common among

the youngest group of patients (birth to < 1 year) across all groups with approximately 10.5% of this

cohort revisiting the ED within 7 days of an index visit. There was a marked difference between

immigrant groups in the ages of children who revisited an ED. For example, within the recent

immigrant group, 72% of revisits were by children 6 years of age and younger. By contrast, within

the non-immigrant group, only 53% of revisits were by children 6 years of age and younger. Across

all groups, a greater proportion of revisits occurred by patients in the lowest income and most

deprived quintiles. Likewise, across all groups, children who were high users of ED’s in the year

preceding the index visit, both for low acuity and overall visits, were more likely to revisit an ED

within 7 days of an index visit. Children with the highest CTAS score (1 or 2) on the initial visit were

more likely to revisit the ED, but this was more common in the recent immigrant group (11.4%

revisits) compared with the non-immigrant group (10.4% revisits). Children most often revisited an

ED if their index visit was in the evening or at a high volume centre.

27

Table 4. Revisits to an ED for pediatric patients living in CMA’s of Ontario from April 2003 to March 2010 by immigrant status and patient and hospital characteristics, n = 3322901

Non-immigrant, n (% within group)

Revisit (%)

Longer-term immigrant, n (% within group)

Revisit (%)

Recent immigrant n (% within group)

Revisit (%)

Total, n (% within group)

Revisit (%)

p-value*

Overall Revisits 210607 7.5 25635 7.5 13406 8.0 249648 7.5 <.001

Patient Characteristics

Age, years 0 - <1 28641 (13.6) 10.6 3477 (13.6) 10.2 3213 (24.0) 9.9 35331 (14.2) 10.5 <.001 1 - 2 43604 (20.7) 8.4 5864 (22.9) 8.7 3977 (29.8) 8.9 53445 (21.4) 8.5 0.002 3 - 6 38840 (18.4) 6.6 6056 (23.6) 6.9 2415 (18.0) 7.2 47311 (19.0) 6.6 <.001 7 - 10 26730 (12.7) 6.1 3770 (14.7) 6.6 1283 (9.6) 6.0 31783 (12.7) 6.2 <.001 11 - 14 34033 (16.2) 6.6 3295 (12.9) 6.3 1260 (9.4) 6.4 38588 (15.5) 6.5 0.035 15 - 17 38759 (18.4) 8.1 3173 (12.4) 7.6 1258 (9.4) 7.8 43190 (17.3) 8.0 <.001

Sex F 98028 (46.5) 7.8 11182 (43.6) 7.7 5672 (42.3) 7.9 114882 (46.0) 7.8 0.190 M 112579 (53.5) 7.3 14453 (56.4) 7.3 7734 (57.7) 8.0 134766 (54.0) 7.3 <.001

Neighbourhood income quintile

1 (lowest) 42220 (20.0) 7.9 7686 (30.0) 7.7 5757 (42.9) 8.2 55663 (22.3) 7.9 <.001 2 41355 (19.6) 7.7 5589 (21.8) 7.4 2845 (21.2) 7.9 49789 (19.9) 7.7 0.006 3 42266 (20.1) 7.5 5102 (19.9) 7.4 2068 (15.4) 8.0 49436 (19.8) 7.5 0.007 4 44663 (21.2) 7.3 4455 (17.4) 7.5 1630 (12.2) 7.6 50748 (20.3) 7.4 0.084 5 (highest) 39366 (18.7) 7.0 2774 (10.8) 7.4 1083 (8.1) 7.8 43223 (17.3) 7.0 <.001

Deprivation index, n (%) 1 (least deprived) 56456 (26.8) 7.2 5743 (22.4) 7.5 2148 (16.0) 7.8 64347 (25.8) 7.3 <.001 2 43204 (20.5) 7.3 4522 (17.6) 7.4 1877 (14.0) 7.9 49603 (19.9) 7.3 <.001 3 36372 (17.3) 7.5 4631 (18.1) 7.6 2408 (18.0) 7.9 43411 (17.4) 7.5 <.001 4 30246 (14.4) 7.7 4280 (16.7) 7.5 2830 (21.1) 8.0 37356 (15.0) 7.7 <.001 5 (most deprived) 34777 (16.5) 8.0 5609 (21.9) 7.6 3595 (26.8) 8.2 43981 (17.6) 7.9 <.001

ED visits in previous year (#), 0 111021 (52.7) 6.6 14945 (58.3) 6.7 8276 (61.7) 7.3 134242 (53.8) 6.7 <.001 1 47072 (22.4) 7.6 5579 (21.8) 8.1 2645 (19.7) 8.3 55296 (22.1) 7.7 <.001 2 22768 (10.8) 8.8 2402 (9.4) 9.2 1216 (9.1) 10.0 26386 (10.6) 8.9 <.001 3+ 29746 (14.1) 11.8 2709 (10.6) 12.1 1269 (9.5) 12.3 33724 (13.5) 11.9 0.200

Low acuity ED visits in previous year (#)

28

0 153991 (73.1) 7.1 20462 (79.8) 7.2 11054 (82.5) 7.8 185507 (74.3) 7.2 <.001 1 36482 (17.3) 8.0 3762 (14.7) 8.5 1654 (12.3) 8.3 41898 (16.8) 8.1 0.002 2 11678 (5.5) 9.4 950 (3.7) 9.7 447 (3.3) 9.8 13075 (5.2) 9.4 0.423 3+ 8456 (4.0) 11.7 461 (1.8) 11.4 251 (1.9) 12.9 9168 (3.7) 11.8 0.239

ED visit characteristics

CTAS 1 - 2 28858 (13.7) 10.4 3858 (15.0) 10.3 2232 (16.6) 11.4 34948 (14.0) 10.4 <.001 3 109462 (52.0) 8.9 14008 (54.6) 8.8 7267 (54.2) 9.2 130737 (52.4) 8.9 0.002 4 - 5 72246 (34.3) 5.5 7768 (30.3) 5.4 3906 (29.1) 5.6 83920 (33.6) 5.5 0.006

Chief complaint index visit Injury/trauma 62821 (29.8) 5.4 6051 (23.6) 4.9 2866 (21.4) 5.2 71738 (28.7) 5.4 <.001 Neurologic 5893 (2.8) 8.8 846 (3.3) 9.1 419 (3.1) 9.9 7158 (2.9) 8.8 0.023 Skin problems 9983 (4.7) 9.7 1032 (4.0) 8.5 511 (3.8) 8.6 11526 (4.6) 9.5 <.001 Administrative issue 3611 (1.7) 6.6 312 (1.2) 5.8 209 (1.6) 5.6 4132 (1.7) 6.5 0.003 General symptoms 3967 (1.9) 8.0 543 (2.1) 8.0 306 (2.3) 7.5 4816 (1.9) 8.0 0.506 Other 23936 (11.4) 9.9 3006 (11.7) 10.2 1468 (11.0) 10.4 28410 (11.4) 10.0 0.057 Mental health 3533 (1.7) 7.7 234 (0.9) 6.3 98 (0.7) 8.0 3865 (1.5) 7.6 0.007 Newborn 3183 (1.5) 17.0 422 (1.6) 15.4 411 (3.1) 13.3 4016 (1.6) 16.4 <.001 Infections 14382 (6.8) 8.9 2424 (9.5) 8.8 1387 (10.3) 9.2 18193 (7.3) 8.9 0.227 Cancer 687 (0.3) 17.6 121 (0.5) 17.1 57 (0.4) 14.6 865 (0.3) 17.3 0.339 Gastrointestinal 25253 (12.0) 14.0 3743 (14.6) 12,8 1885 (14.1) 12.6 30881 (12.4) 13.7 <.001 Asthma 7377 (3.5) 7.4 896 (3.5) 6.4 296 92.2) 6.6 8569 (3.4) 7.2 <.001 URTI/Otitis media 37730 (17.9) 6.7 4582 (17.9) 7.0 2554 (19.1) 7.4 44866 (18.0) 6.8 <.001 Fever 8251 (3.9) 12.4 1423 (5.6) 12.1 939 (7.0) 12.6 10613 (4.3) 12.4 0.466

Shift time Night 25224 (12.0) 7.1 3740 (14.7) 7.0 2122 (15.8) 7.9 31086 (12.5) 7.1 <.001 Day 72769 (34.6) 7.1 8527 (33.3) 7.3 4452 (33.2) 7.7 85748 (34.3) 7.1 <.001 Evening 112614 (53.5) 7.9 13368 (52.1) 7.8 6832 (51.0) 8.2 132814 (53.2) 7.9 <.001

Shift day Weekday 136745 (64.9) 7.5 16528 (64.5) 7.6 8585 (64.0) 8.1 161858 (64.8) 7.5 <.001 Weekend/holiday 73862 (35.1) 7.4 9107 (35.5) 7.4 4821 (36.0) 7.8 87790 (35.2) 7.5 <.001

Hospital Type Community 142054 (67.4) 7.3 18055 (70.4) 7.2 9002 (67.1) 7.5 169111 (67.7) 7.3 <.001 Pediatric 40885 (19.4) 8.6 6174 (24.1) 8.8 3486 (26.0) 9.5 50545 (20.2) 8.7 <.001 Small 7847 (3.7) 8.7 149 (0.6) 8.4 41 (0.3) 8.8 8037 (3.2) 8.7 0.890 Teaching 19821 (9.4) 6.8 1257 (4.9) 7.1 877 (6.5) 7.8 21955 (8.8) 6.9 <.001

Annual hospital pediatric ED volume High (>16,000) 78003 (37.0) 7.9 9756 (38.1) 8.3 4990 (37.2) 8.8 92749 (37.2) 8.0 <.001

29

Low (<10,000) 74215 (35.2) 7.5 5505 (21.5) 7.2 2966 (22.1) 7.8 82686 (33.1) 7.5 <.001 Medium (10,000-

16,000) 58389 (27.7) 6.9 10374 (40.5) 7.1 5450 (40.7) 7.5 74213 (29.7) 7.0 <.001

*= Chi-squared test

30

Table 5 shows the unadjusted and adjusted odds ratios from the logistic regression models for

revisits to the ED by immigration status and by patient and hospital level characteristics. The final

model included age, sex, deprivation index quintile, ED visits in the last year, low acuity visits in the

last year, main reason for visit at the index visit, CTAS score at the index visit, shift time, shift day,

hospital volume, and hospital type. The reported models do not include GEE as there were minimal

differences in the standard errors between regression models with and without GEE. The final

model excluded income quintile as it was collinear with the deprivation index quintile (Table 8).

Alternate models which excluded low acuity ED visits in the year preceding the index visit produced

similar adjusted odds ratios but had a slightly higher Akaike information criterion (AIC) fit statistic

compared with the final model (AIC = 1694411, c-statistic = 0.636 (without low acuity ED visits)

versus AIC = 1642501, c-statistic = 0.636 (final model)).

In terms of immigrant status, in the unadjusted models, recent immigrants had a greater odds of

revisiting an ED (OR 1.07; 95% CI 1.05, 1.09) but these differences were not significant after

adjusting for patient and hospital level variables. There were no significant differences in revisits

between longer-term immigrants and non-immigrants. Patient characteristics that were

significantly associated with ED revisit after adjusting for other variables included age whereby

compared with teenagers (age 15 – 17 years) and infants (< 1 year), children had lower odds of

revisiting an ED (AOR 0.87 95% CI 0.86, 0.89 for age 1 – 2 years, AOR 0.75 95% CI 0.74, 0.76 for age 3

– 6 years, AOR 0.75 95% CI 0.74 – 0.77 for age 7 – 10 years and AOR 0.85 95% CI 0.84, 0.87 for age

11-14 years). Females had a slightly higher odds of revisiting an ED (AOR 1.01; 95% CI 1.00, 1.02),

and those in the two most deprived quintiles also had a higher odds of revisiting an ED (AOR 1.03;

95% CI 1.02, 1.04). Having three or more ED visits in the last year increased the odds of revisit

within 7 days by 80% (AOR 1.80; 95% CI 1.77, 1.83). Children with a high acuity on presentation had

significantly higher odds of revisiting an ED compared with the lowest acuity group (AOR 1.49 95% CI

1.48, 1.51 for CTAS 3, AOR 1.80 95% CI 1.78, 1.83 for CTAS 1 – 2). Children whose initial visit was

during the evening or night had a lower odds of revisiting the ED (AOR 0.77 95% CI 0.76, 0.78 for

night and AOR 0.89 95% CI 0.88, 0.89 for evening). There was no significant difference in the odds

of revisit for visits occurring on a weekend versus weekday. Index visits to small hospitals and those

with low pediatric ED volumes also had higher odds of revisits (AOR 1.18, 95% CI 1.15, 1.22 and AOR

1.05; 95% CI 1.04, 1.06, respectively).

31

Table 5. Unadjusted and adjusted logistic regressions with odds ratios of ED revisits according to patient and hospital characteristics (n = 3322901)

Unadjusted OR (95% CI)

p-value Adjusted OR (95% CI)*†

p-value

Immigrant Status

Non-immigrant Reference - Reference - Longer-term immigrant 1.00 (0.99, 1.02) 0.705 0.99 (0.98, 1.01) 0.252 Recent immigrant 1.07 (1.05, 1.09) <.001 1.01 (0.99, 1.02) 0.553

Patient Characteristics

Age, years

0 - <1 1.35 (1.33, 1.37) <.001 1.02 (1.01, 1.04) 0.007

1 - 2 1.07 (1.05, 1.08) <.001 0.87 (0.86, 0.89) <.001

3 - 6 0.82 (0.81, 0.83) <.001 0.75 (0.74, 0.76) <.001

7 - 10 0.76 (0.75, 0.77) <.001 0.75 (0.74, 0.77) <.001

11 - 14 0.80 (0.79, 0.81) <.001 0.85 (0.84, 0.87) <.001

15 - 17 Reference - Reference -

Sex

F 1.06 (1.06, 1.08) <.001 1.01 (1.00, 1.02) 0.003

M Reference - Reference -

Deprivation quintile

1 (least deprived) Reference - Reference -

2 1.01 (1.00, 1.02) <.001 1.01 (0.99, 1.02) 0.288

3 1.04 (1.03, 1.06) <.001 1.02 (1.01, 1.03) 0.003

4 1.07 (1.05, 1.08) <.001 1.03 (1.01, 1.04) <.001

5 (most deprived) 1.10 (1.09, 1.12) <.001 1.03 (1.02, 1.04) <.001

ED visits in previous year (#),

0 Reference - Reference -

1 1.16 (1.15, 1.18) <.001 1.18 (1.17, 1.20) <.001

2 1.36 (1.35, 1.38) <.001 1.37 (1.35, 1.39) <.001

3+ 1.90 (1.87, 1.92) <.001 1.80 (1.77, 1.83) <.001

Low acuity ED visits in previous year (#)

0 Reference -

-

1 1.14 (1.12, 1.15) <.001 0.96 (0.95, 0.98) <.001

2 1.34 (1.32, 1.37) <.001 0.96 (0.94, 0.98) 0.001

3+ 1.72 (1.69, 1.76) <.001 1.07 (1.04, 1.10) <.001

ED visit characteristics at index visit

CTAS

1 - 2 1.99 (1.96, 2.01) <.001 1.80 (1.78, 1.83) <.001

3 1.67 (1.65, 1.68) <.001 1.49 (1.48, 1.51) <.001

4 - 5 Reference - Reference -

Chief complaint index visit

Injury/trauma Reference - Reference -

Neurologic 1.72 (1.67, 1.76) <.001 1.32 (1.29, 1.36) <.001

Skin problems 1.86 (1.82, 1.90) <.001 1.80 (1.76, 1.84) <.001

Administrative issue 1.23 (1.19, 1.27) <.001 1.04 (1.01, 1.08) 0.012

General symptoms 1.53 (1.48, 1.58) <.001 1.32 (1.28, 1.36) <.001

Other 1.95 (1.92, 1.98) <.001 1.66 (1.64, 1.69) <.001

Mental health 1.45 (1.41, 1.50) <.001 1.08 (1.04, 1.12) <.001

Newborn 3.45 (3.34, 3.57) <.001 2.47 (2.38, 2.57) <.001

Infectious problems 1.72 (1.69, 1.75) <.001 1.50 (1.47, 1.52) <.001

Cancer 3.68 (3.42, 3.96) <.001 2.70 (2.49, 2.90) <.001

32

Gastrointestinal 2.80 (2.76, 2.84) <.001 2.42 (2.38, 2.46) <.001

Asthma 1.37 (1.34, 1.40) <.001 1.03 (1.01, 1.06) 0.013

URTI/Otitis media 1.28 (1.26, 1.30) <.001 1.14 (1.12, 1.15) <.001

Fever 2.49 (2.44, 2.55) <.001 2.04 (1.99, 2.09) <.001

Shift time

Night 0.90 (0.89, 0.91) <.001 0.77 (0.76, 0.78) <.001

Day Reference - Reference -

Evening 0.90 (0.89, 0.91) <.001 0.89 (0.88, 0.89) <.001

Shift day

Weekday Reference - Reference -

Weekend/holiday 0.99 (0.98, 1.00) 0.004 1.00 (0.99, 1.01) 0.773

Hospital Type

Community 0.82 (0.82, 0,83) <.001 0.86 (0.85, 0.87) <.001

Pediatric Reference - Reference -

Small 1.01 (0.98, 1.03) 0.56 1.18 (1.15, 1.22) <.001

Teaching 0.78 (0.77, 0.79) <.001 0.77 (0.76, 0.79) <.001

Annual hospital pediatric ED volume

High (>16,000) Reference - Reference -

Low (<10,000) 0.93 (0.92, 0.94) <.001 1.05 (1.04, 1.06) <.001

Medium (10,000-16,000) 0.86 (0.85, 0.87) <.001 0.96 (0.94, 0.97) <.001 *= adjusted for immigration status, age, sex, deprivation index, low acuity ED visits in past year, ED visits in past year, CTAS score, chief complaint, shift time, shift day, hospital type, hospital volume. †Missing = 146583

4.5.2 Association of immigrant category, native language, official language of country of birth, and

region of origin with ED revisits

Table 6 shows the association of ED revisits by immigrants based on immigration category, native

tongue declared upon landing in Canada, official language of country of birth, and region of origin

(birth). Economic class immigrants had the lowest rates of revisiting an ED compared with other

immigrant groups (7.4% Economic class, 7.9% Family class, and 7.8% Refugee class). Those whose

native tongue was not English or French had the highest rate of ED revisits (7.8%). Similarly, those

who had English as an official language of their country of birth had the lowest rates of revisits

(7.2%). Patients had the lowest revisit rates if they were from industrialized nations (7.3%) and

highest from South and East Asia (8.0% and 7.8%, respectively).

33

Table 6. Revisits to an ED for pediatric immigrants living in CMA’s of Ontario from April 2003 to March 2010 by immigration characteristics

Immigration characteristics n = 509519

Longer-term immigrant, n (% within group)

Revisit (%) Recent immigrant, n (% within group)

Revisit (%) Total, n (% within group)

Revisit (%)

*p-value

Immigration Category Economic 8881 (34.6) 7.3 5419 (40.4) 7.5 14300 (36.6) 7.4 0.145 Family 12053 (47.0) 7.6 4789 (35.7) 8.7 16842 (43.1) 7.9 <.001 Refugee 4701 (18.3) 7.7 3198 (23.8) 8.0 7899 (20.2) 7.8 0.079

Native tongue English 4410 (17.2) 7.1 1306 (9.7) 7.2 5716 (14.6) 7.1 0.365 French 106 (0.4) 7.8 98 (0.7) 7.0 204 (0.5) 7.4 0.428 No English or French 21119 (82.4) 7.6 12002 (90.0) 8.1 33121 (84.8) 7.8 <.001

Country with official language English 3932 (15.3) 7.0 1323 (9.9) 7.5 5255 (13.5) 7.2 0.028 French 404 (1.6) 7.9 364 (2.7) 8.0 768 (2.0) 7.9 0.897 No English or French 21299 (83.1) 7.6 11719 (87.4) 8.0 33018 (84.6) 7.8 <.001

Region of origin Central and Eastern Europe 2065 (8.1) 7.3 1141 (8.5) 7.9 3206 (8.2) 7.5 0.029 East Asia 4949 (19.3) 7.6 2697 (20.1) 8.8 7646 (19.6) 8.0 <.001 Eastern and Southern Africa 1561 (6.1) 7.7 830 (6.2) 7.9 2391 (6.1) 7.8 0.478 Industrialized 3701 (14.4) 7.2 157(11.8) 7.6 5277 (13.5) 7.3 0.088 Latin American and Caribbean 4834 (18.9) 7.4 1708 (12.7) 8.0 6542 (16.8) 7.5 0.004 Middle East and North Africa 2237 (8.7) 7.5 1492 (11.1) 7.5 3729 (9.6) 7.5 0.960 South Asia 5850 (22.8) 7.8 3628 (27.1) 7.8 9478 (24.3) 7.8 0.583 West and Central Africa 438 (1.7) 7.3 328 (2.4) 7.9 766 (2.0) 7.6 0.263 * = Chi-squared test

34

Table 7 shows the unadjusted and adjusted odds ratios using multiple logistic regression for ED

revisits by immigrant subgroup. The final model was adjusted for age, sex, deprivation quintile, ED

use in the previous year, low acuity ED use in the previous year, CTAS score at the index visit, chief

complaint, shift time, shift day, hospital pediatric ED volume, hospital type, immigration category,

native tongue, region of origin, and immigration timing. Language of country of birth and income

quintile were excluded from the model due to collinearity with native tongue and deprivation index.

In the adjusted models, there were no differences in the odds of revisiting an ED based on

immigration category. However, in patients whose native tongue was not English or French the

odds of revisiting an ED was significantly higher compared to English speakers (AOR 1.05 95% CI

1.01, 1.09). There were no significant differences in the odds of revisit based on the region of origin

or recency of immigration, though recent immigrants trended towards having a higher odds of

revisit (AOR 1.02 95% CI 1.00, 1.04).

Table 7. Unadjusted and adjusted logistic regressions with odds ratios of ED revisits according to immigration characteristics (n = 509518)

Unadjusted OR (95% CI)

p-value Adjusted OR (95% CI)*†

p-value

Immigration Characteristics

Immigration Category

Economic Reference - Reference - Family 1.08 (1.05, 1.10) <.001 1.02 (1.00, 1.05) 0.089 Refugee 1.07 (1.04, 1.10) <.001 1.02 (0.99, 1.06) 0.183

Native Tongue English Reference - Reference -

French 1.04 (0.90, 1.21) 0.5600 0.99 (0.85, 1.15) 0.897

No English or French 1.10 (1.07, 1.13) <.001 1.05 (1.01, 1.09) 0.008

Region of origin

Central and Eastern Europe 1.03 (0.98, 1.08) 0.245 0.99 (0.94, 1.04) 0.691

East Asia 1.10 (1.06, 1.14) <.001 1.03 (0.99, 1.08) 0.109

Eastern and Southern Africa 1.07 (1.01, 1.12) 0.012 0.99 (0.94, 1.04) 0.663

Industrialized Reference - Reference -

Latin American and Caribbean 1.03 (0.99, 1.07) 0.144 0.98 (0.94, 1.02) 0.314

Middle East and North Africa 1.02 (0.98, 107) 0.327 1.00 (0.96, 1.05) 0.976

South Asia 1.07 (1.03, 1.11) <.001 1.02 (0.98, 1.06) 0.300

West and Central Africa 1.03 (0.95, 1.12) 0.430 0.93 (0.86, 1.01) 0.094

Immigration Timing Recent 1.07 (1.05, 1.09) <.001 1.02 (1.00, 1.04) 0.078 Longer-term Reference - Reference - *=Adjusted for age, sex, deprivation quintile, ED use in previous year, low acuity ED use in previous year, CTAS score at index visit, chief complaint, shift time, shift day, hospital pediatric ED volume, hospital type, immigration category, native tongue, region of origin, immigration time (longer-term/recent) † Missing 18809 patients in adjusted models

35

4.5.3 Assessment of multi-collinearity of independent variables for ED revisits

Table 8 shows the variance inflation factor and tolerance for the independent variables. The Ontario

Marginalization Index material deprivation quintile was correlated with neighbourhood income

quintile with variance inflation factors of 2.4 and tolerance 0.4. Both measures reflect

socioeconomic status of the patient’s neighbourhood within a dissemination area. However, the

Ontario Marginalization Index has been shown to be stable over time [70] and therefore the

deprivation index within the Ontario Marginalization Index was left in the model and income

quintile was not included in the models. Similarly, native tongue and official language of country of

birth were collinear therefore only native tongue was used in the models. This variable was chosen

as it likely more accurately acts as a proxy for knowledge of English or French compared with the

official language of the country of birth.

Table 8. Tolerance and variance inflation factors for independent variables for ED revisits

Variable Tolerance VIF

Immigrant status 0.885 1.045 Age 0.995 1.131 Sex 0.915 1.005 CTAS score at visit 0.904 1.093 Chief complaint at visit 0.904 1.106 Hospital type 0.898 1.113 Marginalization index – material deprivation 0.401 2.492 Shift day 0.993 1.007 Neighbourhood income quintile 0.404 2.472 ED visits in previous 1 year 0.546 1.832 Shift time 0.978 1.022 Annual hospital pediatric volume 0.916 1.092 Low acuity ED visits in previous 1 year 0.553 1.807 Native language 0.299 3.348 Language of country of origin 0.294 3.402 Region of origin 0.893 1.119

4.6 Secondary outcome: Revisits leading to admission

Of the 249 606 revisits to the ED within 7 days of an index visit with disposition data available, 12.7%

of patients were admitted or died. Only 15 patients during the study period died on the revisit and

therefore further subgroup analysis was not performed. The groups were then dichotomized to

36

discharged or admitted/death. Recent immigrants were more likely to be admitted to hospital/died

on the revisit (14.8%) compared with non-immigrants (12.5%) (Table 9).

Table 9. Overall ED revisits leading to admission or death from April 2003 to March 2010, n = 249648†

Non-immigrant n (%)

Longer-term immigrant n (%)

Recent immigrant n (%)

Overall N (%)

p-value*

Admitted/Died 26245 (12.5) 3570 (13.9) 1988 (14.8) 31803 (12.7) <0.001 *Chi-squared test † Revisit disposition data missing for 42 patients

4.6.1 Association of immigrant status with revisits leading to admission

Table 10 shows the revisits to an ED that led to admission to hospital/death based on immigrant

status. Overall, younger patients were more often admitted on the revisit and this did not differ

across immigrant groups. Outside of the infant (0 to < 1 year) group, longer-term immigrants had a

significantly higher proportion of revisits leading to admission compared with the non-immigrant

groups when stratified by age group. Little differences existed across deprivation index quintiles for

rates of admission. Children who had a high number (3+) of low acuity ED visits in the preceding

year had much lower proportions of admissions on the revisit (7.0% admissions for those with 3+

low acuity ED visits and 13.8% admissions for those with no low acuity visits). Children who had a

CTAS score of 3 at their index visit were almost twice as likely to be admitted on the revisit

compared with children who had a low acuity (4-5) CTAS score. Index visits occurring at night were

more likely to result in an admission (16.7%, night versus 11.5%, evening) and this trend was

consistent across immigrant status groups.

37

Table 10. Characteristics of pediatric patients from urban Ontario who revisited an ED and were admitted/died on the revisit according to immigrant status

Non-immigrant, n

Admitted (%)

Longer-term immigrant, n

Admitted (%)

Recent immigrant, n

Admitted (%)

TOTAL, n Admitted (%)

p-value*

Patient Characteristics n = 210569 n = 25631 n = 13406 n = 249606

Age, years 0 - <1 5480 19.1 654 18.8 616 19.2 6750 19.1 0.898 1 - 2 5810 13.3 853 14.6 570 14.3 7233 13.5 0.012 3 - 6 4675 12.0 782 12.9 316 13.1 5773 12.2 0.061 7 - 10 2815 10.5 527 14.9 176 13.7 3518 11.1 <.001 11 - 14 3475 10.2 400 12.1 144 11.4 4019 10.4 0.001 15 - 17 3990 10.3 354 11.2 166 13.2 4510 10.5 0.002

Sex F 11815 12.1 1499 13.4 823 14.5 14137 12.3 <.001 M 14430 12.8 2071 14.3 1165 15.1 17666 13.1 <.001

Deprivation index quintile 1 (least deprived)) 7109 12.6 752 13.1 297 13.8 8158 12.7 0.148 2 5365 12.4 642 14.2 263 14.0 6270 12.6 <.001 3 4582 12.6 694 15.0 381 15.8 5657 13.0 <.001 4 3728 12.3 615 14.4 430 15.2 4773 12.8 <.001 5 (most deprived) 4304 12.4 748 13.3 527 14.7 5579 12.7 <.001

ED visits in previous year 0 14071 12.7 2059 13.8 1290 15.6 17420 13.0 <.001 1 5511 11.7 752 13.5 359 13.6 6622 12.0 <.001 2 2776 12.2 321 13.4 162 13.3 3259 12.4 <.001 3+ 3887 13.1 438 16.2 177 14.0 4502 13.4 <.001

Low acuity ED visits in previous year

0 20839 13.5 2010 14.7 1747 15.8 25596 13.8 <.001 1 3750 10.3 435 11.6 191 11.6 4376 10.5 0.016 2 1050 9.0 99 10.4 38 8.5 1187 9.1 0.308 3+ 606 7.2 26 5.6 12 4.8 644 7.0 0.169

Index ED visit characteristics

CTAS 1 - 2 (Resuscitation) <6 n/a <6 n/a <6 n/a 6 14.0 0.02

38

3 (Emergent) 6666 23.1 967 25.1 539 24.2 8172 23.4 <.001 4 - 5 (Non-urgent) 15246 13.9 2065 14.7 1151 15.8 18462 14.1 <.001

Chief complaint at the index visit Injury/trauma 4353 6.9 558 9.2 282 9.8 5193 7.2 <.001 Neurologic 1167 19.8 165 19.5 91 21.7 1423 19.9 0.614 Skin problems 709 7.1 82 8.0 58 11.4 849 7.4 0.001 Administrative issue 403 11.2 33 10.6 36 17.2 472 11.4 0.025 General symptoms 517 13.0 67 12.3 46 15.0 630 13.1 0.52 Other 3962 16.6 503 16.7 272 18.5 4737 16.7 0.144 Mental health 853 24.2 54 23.1 28 28.6 935 24.2 0.555 Newborn 549 17.3 81 19.2 66 16.1 696 17.3 0.472 Infections 2061 14.3 346 14.3 216 15.6 2623 14.4 0.444 Cancer 222 32.3 43 35.5 12 21.1 277 32.0 0.145 Gastrointestinal 4082 16.2 595 15.9 324 17.2 5001 16.2 0.445 Asthma 1588 21.5 209 23.3 69 23.3 1866 21.8 0.38 URTI/Otitis media 4555 12.1 634 13.8 351 13.7 5540 12.4 <.001 Fever 1224 14.8 200 14.1 137 14.6 1561 14.7 0.741

Shift time Night 4159 16.5 657 17.6 361 17.0 5177 16.7 0.229 Day 9386 12.9 1246 14.6 701 15.8 11333 13.2 <.001 Evening 12700 11.3 1667 12.5 926 13.6 15293 11.5 <.001

Shift day Weekday 16954 12.4 2322 14.1 1258 14.7 20534 12.7 <.001 Weekend/holiday 9291 12.6 1248 13.7 730 15.1 11269 12.8 <.001

Hospital Type Community 18381 12.9 2613 14.5 1438 16.0 22432 13.3 <.001 Pediatric 4863 11.9 770 12.5 434 12.5 6067 12.0 0.303 Small 484 6.2 <6 - <6 - 492 6.1 0.347 Teaching 2517 12.7 182 14.5 113 12.9 2812 12.8 0.182

Annual hospital pediatric ED volume High (>16,000) 9713 12.5 1352 13.9 717 14.4 11782 12.7 <.001 Low (<10,000) 8242 11.1 686 12.5 416 14.0 934 11.3 <.001 Medium (10,000-

16,000) 8290 14.2 1532 14.8 855 15.7 10677 14.4

0.006

*= Chi-squared test

39

Table 11 shows the unadjusted and adjusted odds ratios from the logistic regression models of ED

revisits leading to admission. In the unadjusted models, both longer-term and recent immigrants

had higher odds of being admitted on the revisit (OR 1.14 95% CI 1.10, 1.18 and OR 1.22 95% CI

1.16, 1.28, respectively) though after adjusting for covariates, these differences no longer reached

statistical significance. In the adjusted models, infants had a 62% higher odds of admission on the

revisit compared with the oldest age group. This effect was still observed across all age groups

though diminished with increasing age. There were no differences across deprivation index

quintiles for odds of admission on the revisit. Children who were frequent ED users had higher

odds (AOR 1.34 95% CI 1.28, 1.41) of admission on the revisit compared to low frequency users

though the opposite trend was observed in children with multiple low acuity visits in the year

preceding the index visit (AOR 0.45, 95% CI 0.41, 0.50 for high frequency users). Children with high

acuity at the index visit had more than a three-fold higher odds of admission on the revisit

compared with children with low acuity visits (AOR 3.31 95% CI 3.18, 3.45 for CTAS 1 -2 and 1.96

95% CI 1.89, 2.02 for CTAS 3).

Table 11. Unadjusted and adjusted logistic regressions with odds ratios of ED revisits leading to admission according to patient and hospital characteristics (n = 249648)

Unadjusted OR (95% CI)

p-value Adjusted OR (95% CI)*†

p-value

Immigrant Status

Non-immigrant Reference - Reference - Longer-term immigrant 1.14 (1.10, 1.18) <.001 1.03 (0.99, 1.08) 0.102 Recent immigrant 1.22 (1.16, 1.28) <.001 1.05 (0.99, 1.10) 0.092

Patient Characteristics

Age, years

0 - <1 2.02 (1.94, 2.11) <.001 1.62 (1.55, 1.70) <.001

1 - 2 1.34 (1.29, 1.40) <.001 1.26 (1.20, 1.32) <.001

3 - 6 1.19 (1.14, 1.24) <.001 1.23 (1.18, 1.29) <.001

7 - 10 1.07 (1.02, 1.12) 0.006 1.15 (1.09, 1.20) <.001

11 - 14 1.00 (0.95, 1.04) 0.895 1.12 (1.07, 1.17) <.001

15 - 17 Reference - Reference -

Sex

F 0.93 (0.91, 0.95) <.001 0.94 (0.92, 0.97) <.001

M Reference - Reference -

Deprivation quintile

1 (least deprived) Reference - Reference -

2 1.00 (0.96, 1.03) 0.846 1.01 (0.97, 1.04) 0.711

3 1.03 (1.00, 1.07) 0.088 1.02 (0.98, 1.06) 0.304

4 1.01 (0.97, 1.05) 0.654 0.99 (0.95, 1.03) 0.480

5 (most deprived) 1.00 (0.96, 1.04) 0.981 0.97 (0.94, 1.01) 0.147

ED visits in previous year (#),

0 Reference - Reference -

1 0.91 (0.88, 0.94) <.001 1.00 (0.97, 1.04) 0.643

40

2 0.94 (0.91, 0.98) 0.006 1.11 (1.06, 1.17) <.001

3+ 1.03 (1.00, 1.07) 0.069 1.34 (1.28, 1.41) <.001

Low acuity ED visits in previous year (#)

0 Reference - Reference -

1 0.73 (0.70, 0.75) <.001 0.75 (0.72, 0.78) <.001

2 0.62 (0.59, 0.66) <.001 0.61 (0.56, 0.65) <.001

3+ 0.47 (0.44, 0.51) <.001 0.45 (0.41, 0.50) <.001

Index ED visit characteristics

CTAS

1 - 2 4.66 (4.48, 4.83) <.001 3.31 (3.18, 3.45) <.001

3 2.51 (2.43, 2.59) <.001 1.96 (1.89, 2.02) <.001

4 - 5 Reference - Reference -

Chief complaint index visit

Injury/trauma Reference - Reference -

Neurologic 3.18 (2.98, 3.39) <.001 2.05 (1.92, 2.20) <.001

Skin problems 1.02 (0.94, 1.10) 0.626 1.00 (0.92, 1.08) 0.973

Administrative issue 1.65 (1.50, 1.83) <.001 1.40 (1.26, 1.55) <.001

General symptoms 1.93 (1.76, 2.11) <.001 1.46 (1.33, 1.60) <.001

Other 2.56 (2.46, 2.68) <.001 1.94 (1.85, 2.02) <.001

Mental health 4.10 (3.79, 4.44) <.001 3.51 (3.23, 3.82) <.001

Newborn 2.69 (2.46, 2.93) <.001 1.36 (1.24, 1.50) <.001

Infections 2.16 (2.05, 2.27) <.001 1.66 (1.57, 1.75) <.001

Cancer 6.04 (5.22, 6.98) <.001 4.04 (3.47, 4.71) <.001

Gastrointestinal 2.48 (2.38, 2.58) <.001 1.91 (1.83, 3.00) <.001

Asthma 3.57 (3.36, 3.78) <.001 2.22 (2.09, 2.37) <.001

URTI/Otitis media 1.80 (1.74, 1.88) <.001 1.36 (1.30, 1.42) <.001

Fever 2.21 (2.08, 2.35) <.001 1.48 (1.39, 1.58) <.001

Shift time

Night Reference - Reference -

Day 1.54 (1.48, 1.59) <.001 1.32 (1.28, 1.37) <.001

Evening 1.17 (1.14, 1.20) <.001 1.18 (1.15, 1.21) <.001

Shift day

Weekday Reference - Reference -

Weekend/holiday 1.01 (0.90, 1.04) 0.284 1.03 (1.00, 1.05) 0.048

Hospital Type

Community 1.12 (1.09, 1.17) <.001 1.15 (1.10, 1.20) <.001

Pediatric Reference - Reference -

Small 0.48 (0.44, 0.53) <.001 0.85 (0.76, 0.95) 0.003

Teaching 1.08 (1.03, 1.13) 0.002 1.15 (1.08, 1.21) <.001

Annual hospital pediatric ED volume

High (>16,000) Reference - Reference -

Low (<10,000) 0.88 (0.85, 0.90) <.001 0.99 (0.95, 1.02) 0.509

Medium (10,000-16,000) 1.12 (1.12, 1.19) <.001 1.03 (1.00, 1.067) 0.065 *= adjusted for age, sex, deprivation index, low acuity ED visits in past year, ED visits in past year, CTAS score, chief complaint, shift time, shift day, hospital type, hospital volume. †Missing = 42

41

4.6.2 Association of immigrant category, native language, official language of country of birth, and

region of origin with revisits leading to admission

Table 12 shows the revisits leading to admission based on immigrant category, native language,

official language of country of birth, and region of origin. Revisits leading to admission were highest

in Family class immigrants with 15.2% of this class being admitted on the revisit. This pattern of

admission was observed in both recent and longer-term immigrants. There were no differences in

the proportion of patients admitted based on the native tongue of the immigrant though

immigrants born in countries with English as an official language had the highest proportion of

admitted patients (15.3% versus 14.1% in the non-English or French group). There were significant

differences in the proportion admitted on the revisit depending on the country of origin. Children

from West and Central Africa and South Asia had the highest proportion of admissions on the revisit

(20.1% and 17.1%, respectively). In contrast, children from industrialized regions only had 12.7% of

children admitted on the revisit.

42

Table 12. Revisits to an ED leading to admission based on immigrant characteristics (n = 39037)

Immigration characteristics Longer-term immigrant, n

Admission (%)

Recent immigrant, n

Admission (%)

Total, n

Admission (%)

p-value*

Immigration Category <.001 Economic 1192 13.4 771 14.2 1963 13.7 Family 1791 14.9 764 16.0 2555 15.2 Refugee 587 12.5 453 14.2 1040 13.2

Native tongue 0.068 English 669 15.2 199 15.2 868 15.2 French 13 12.3 19 19.4 32 15.7 No English or French 2888 13.7 1770 14.8 4658 14.1

Country with official language 0.034 English 591 15.0 212 16.1 803 15.3 French 43 10.6 54 14.8 97 12.6 No English or French 2936 13.8 1722 14.7 4658 14.1

Region of origin <.001 Central and Eastern Europe 223 10.8 124 10.8 347 10.8 East Asia 686 13.9 382 14.2 1068 14.0 Eastern and Southern Africa 189 12.1 108 13.0 297 12.4 Industrialized 452 12.2 220 14.0 672 12.7 Latin American and Caribbean 687 14.2 227 13.3 914 14.0 Middle East and North Africa 274 12.3 207 13.9 481 12.9 South Asia 968 16.6 657 18.1 1625 17.1 West and Central Africa 91 20.8 63 19.2 154 20.1 *=Chi-squared test

43

Table 13 shows the unadjusted and adjusted odds ratios from the univariate and multiple logistic

regression models of the ED visits leading to admission according to immigration characteristics.

After adjusting for age, sex, deprivation index, ED use in the previous year, low acuity ED use in the

previous year, CTAS score at the index visit, chief complaint, shift time, shift day, hospital pediatric

ED volume, hospital type, immigration category, native tongue, region of origin, and immigration

timing, there were no significant differences between revisits leading to admission between

immigration categories. Language of country of birth and income quintile were excluded from the

model due to collinearity with native tongue and deprivation index. In this model, those with a

native tongue that was not English or French had a significantly lower odds of admission to hospital

on the revisit (AOR 0.87, 95% CI 0.79, 0.97). The odds of revisits leading to admission were much

higher in the West and Central African immigrants (AOR 1.45 95% CI 1.18, 1.79) and South Asian

immigrants (AOR 1.27 95% CI 1.15, 1.42) compared with those from industrialized nations. Recency

of immigration was not associated with an increased odds of admissions on the revisit.

Table 13. Unadjusted and adjusted odds ratios of ED revisits leading to admission according to immigration characteristics

Unadjusted OR (95% CI)

p-value Adjusted OR (95% CI)*†

p-value

Immigration Characteristics ( n = 39037)

Immigration Category

Economic Reference - Reference -

Family 1.12 (1.06, 1.20) <.001 1.01 (0.95, 1.09) 0.705

Refugee 0.95 (0.88, 1.03) 0.242 0.95 (0.87, 1.04) 0.299

Native Tongue

English Reference - Reference -

French 1.04 (0.71, 1.53) 0.845 1.05 (0.76, 1.59) 0.809

No English or French 0.91 (0.84, 0.99) 0.025 0.87 (0.79, 0.97) 0.009

Region of origin

Central and Eastern Europe 0.83 (0.73, 0.96) 0.929 0.88 (0.76, 1.01) 0.074

East Asia 1.11 (1.00, 1.23) 0.009 1.08 (0.96, 1.20) 0.212

Eastern and Southern Africa 0.97 (0.84, 1.13) 0.044 1.00 (0.85, 1.17) 0.951

Industrialized Reference - Reference -

Latin American and Caribbean 1.11 (1.00, 1.24) 0.050 0.99 (0.88, 1.12) 0.909

Middle East and North Africa 1.02 (0.90, 1.15) 0.811 1.02 (0.90, 1.17) 0.727

South Asia 1.42 (1.29, 1.56) <.001 1.27 (1.15, 142) <.001

West and Central Africa 1.72 (1.42, 2.09) <.001 1.45 (1.18, 1.79) <.001

Immigration Timing Recent 1.08 (1.01, 1.14) 0.012 1.03 (0.96, 1.10) 0.428 Longer-term Reference - Reference - *=Adjusted for age, sex, deprivation quintile, ED use in previous year, low acuity ED use in previous year, CTAS score at index visit, chief complaint, shift time, shift day, hospital pediatric ED volume, hospital type, immigration category, native tongue, region of origin, immigration time (longer-term/recent) † Missing 1400 patients in adjusted models

44

4.6.3 Assessment of multi-collinearity of independent variables for revisits leading to admission

Table 14 shows the variance inflation factor and tolerance for the independent variables. As with

the previous outcome measures, the Ontario Marginalization Index deprivation score was correlated

with neighbourhood income quintile with a variance inflation factors of 2.5 and tolerance of 0.4 and

the deprivation index was chosen as a proxy for socioeconomic status given its stability over time

relative to neighbourhood income quintile [70]. Similarly, native tongue was collinear with official

language of country of birth and therefore the latter was excluded from the model.

Table 14. Tolerance and variance inflation factors for independent variables for ED revisits leading to admission

Variable Tolerance VIF

Immigrant status 0.952 1.050 Age 0.904 1.106 Sex 0.994 1.005 CTAS score at visit 0.939 1.065 Chief complaint at visit 0.956 1.046 Hospital type 0.870 1.149 Marginalization index – material deprivation 0.408 2.450 Shift day 0.996 1.004 Neighbourhood income quintile 0.404 2.473 ED visits in previous 1 year 0.581 1.722 Shift time 0.984 1.0142 Annual hospital pediatric volume 0.892 1.1236 Low acuity ED visits in previous 1 year 0.586 1.706 Native tongue 0.304 3.287 Language of country of birth 0.300 3.329 Region of origin 0.903 1.107

45

4.7 Secondary outcome: Revisits leading to worse CTAS score on the revisit

The number of revisits leading to a worse CTAS score by immigrant group and overall are shown in

Table 15. 18.6% of patients had a worse CTAS score on the revisit with recent immigrants having the

highest proportion of patients with a worse CTAS score on the revisit (19.4%). Of the patients that

returned with a worse CTAS score, 20.5% were admitted. In comparison, of those admitted, 30.0%

returned with a worse CTAS score.

Table 15. ED revisits leading to a worse CTAS score on the revisit (n = 249648)

CTAS score change on revisit

Non-immigrant, n (%)

Longer-term immigrant,

n (%)

Recent immigrant,

n (%)

Total, n (%)

p-value*

Worse 39000 (18.5) 4865 (19.0) 2599 (19.4) 46464 (18.6) 0.009 *= Chi-squared test **Missing return CTAS score for 314 patients

4.7.1 Association of immigrant status with revisits leading to worse CTAS score

The characteristics of patients and their visits for patients who revisited an ED and had a worse CTAS

score at the revisit are shown in Table 16. Non-immigrant infants <1 year old and between 15 – 17

years old had higher proportions of ED revisits with a worse CTAS score compared with the other

immigrant groups. No other differences between immigrant status existed across the remaining age

groups. Revisits with a worse CTAS score were not different between immigrant groups stratified by

deprivation index and there was a general trend that with increasing deprivation, there was an

increasing proportion of patients returning with a worse CTAS score. Both frequent and low acuity

frequent ED users had higher proportions of patients returning with a worse CTAS score compared

with those who didn’t use the ED frequently in the past year (21.7% for 3+ visits versus 17.5% for no

visits and 20.4% versus 18.3% for low acuity ED users). Children with visits to pediatric hospitals

were most likely to return with a higher CTAS score compared with other hospital types. Within

pediatric hospitals, visits by longer-term immigrants were more likely to result in a higher CTAS

score on the revisit (23.1% longer-term immigrants versus 20.8% non-immigrants).

46

Table 16. Characteristics of pediatric patients from urban Ontario who revisited an ED and had a worse CTAS score on the revisit according to immigrant status

Non-

immigrant %

Longer-term

immigrant %

Recent immigrant

% TOTAL % p-value*

Patient Characteristics n = 210336

n = 25591

n = 13365

n = 249292

Age, years 0 - <1 6208 21.7 712 20.5 641 20.0 7561 21.4 0.033 1 - 2 9376 21.5 1294 22.1 876 22.1 11546 21.6 0.457 3 - 6 7599 19.6 1230 20.4 487 20.2 9316 19.7 0.318 7 - 10 4555 17.1 652 17.3 236 18.5 5443 17.2 0.406 11 - 14 5178 15.2 506 15.4 194 15.4 5878 15.3 0.960 15 - 17 6084 15.7 471 14.9 165 13.2 6720 15.6 0.024

Sex

F 18081 18.5 2110 18.9 1112 19.7 21303 18.6 0.047 M 20919 18.6 2755 19.1 1487 18.7 25161 18.7 0.151

Deprivation index quintile

1 (least deprived) 10332 18.3 1072 18.7 392 18.3 11796 18.4 0.785 2 7635 17.7 819 18.1 330 17.6 8784 17.7 0.752 3 6733 15.5 832 18.0 469 19.5 8034 18.5 0.298 4 5713 18.9 840 19.6 572 20.2 7125 19.1 0.139 5 (most deprived) 6914 19.9 1117 20.0 740 20.7 8771 20.0 0.545

ED visits in previous year

0 19234 17.4 2675 17.9 1477 17.9 23386 17.5 0.114 1 8879 18.9 1063 19.1 536 20.3 10478 19.0 0.184 2 4485 19.7 498 20.8 298 24.6 5281 20.0 <.001 3+ 6402 21.6 629 23.3 288 22.8 7319 21.7 0.078

Low acuity ED visits in previous year 0 27985 18.2 3805 18.6 2093 19.0 3383 18.3 0.048 1 6980 19.2 751 20.0 358 21.7 8089 19.3 0.021 2 2320 19.9 211 22.3 98 21.9 2629 20.1 0.133 3+ 1715 20.3 98 21.3 50 20.1 1863 20.4 0.870

Index ED visit characteristics

CTAS

1 - 2 (Resuscitation) n/a n/a n/a n/a n/a n/a n/a n/a n/a 3 (Emergent) 12309 11.3 1613 11.5 908 12.5 14830 11.4 0.003 4 - 5 (Non-urgent) 26691 37.0 3252 41.9 1691 43.4 31634 37.7 <.001

47

Chief complaint at the index visit

Injury/trauma 9119 14.5 1023 17.0 465 16.3 10607 14.8 <.001 Neurologic 940 16.0 143 16.9 56 13.4 1139 15.9 0.265 Skin problems 2052 20.6 196 19.0 104 20.4 2352 20.4 0.486 Administrative issue 775 21.5 75 24.1 57 27.3 907 22.0 0.096 General symptoms 871 22.0 141 26.1 60 19.7 1072 22.3 0.053 Other 4576 19.2 564 18.8 283 19.3 5423 19.1 0.879 Mental health 705 20.0 41 17.6 20 20.4 766 19.9 0.663 Newborn 436 13.7 51 12.1 57 13.9 544 13.6 0.632 Infections 3290 22.9 510 21.1 314 22.8 4114 22.7 0.133 Cancer 136 19.8 28 23.1 11 19.3 175 20.3 0.693 Gastrointestinal 3821 15.2 558 14.9 332 17.7 4711 15.3 0.012 Asthma 1529 20.7 190 21.2 60 20.3 1779 20.8 0.933 URTI/Otitis media 9278 24.6 1076 23.5 624 24.5 10978 24.5 0.260 Fever 1472 17.9 269 18.9 156 16.6 1897 17.9 0.351

Shift time

Night 5333 21.2 818 21.9 448 21.2 6599 21.3 0.586 Day 14354 19.8 1685 19.8 877 19.8 16916 19.8 0.996 Evening 19313 17.2 2362 17.7 1274 18.7 22949 17.3 0.002

Shift day

Weekday 24548 18.0 3074 18.6 1592 18.6 29214 18.1 0.054 Weekend/holiday 14452 19.6 1791 19.7 1007 21.0 17250 19.7 0.067

Hospital Type

Community 25234 17.8 3209 17.8 1624 18.1 30067 17.8 0.787 Pediatric 8480 20.8 1423 23.1 781 22.6 10684 21.2 <.001 Small 1394 17.8 19 12.8 10 24.4 1423 17.7 0.15 Teaching 3892 19.7 214 17.2 184 21.1 4290 19.6 0.049

Annual hospital pediatric ED volume

High (>16,000) 15210 19.5 2040 21.0 1026 20.7 18276 19.7 <.001 Low (<10,000) 13347 18.0 984 17.9 580 19.6 14911 18.1 0.084 Medium (10,000-16,000) 10443 17.9 1841 17.8 993 18.2 13277 17.9 0.76 *= Chi-squared test

48

48

The unadjusted and adjusted odds ratios for ED revisits leading to a worse CTAS score from logistic

regression models are displayed in Table 17. In the adjusted models, no differences in CTAS score

changes were observed between immigrant groups. The youngest age group had over twice the

odds of returning with a worse CTAS score compared with the oldest (15 – 17 years) age group (AOR

2.36 95% CI 2.26, 2.47) with stepwise decrease in odds with an increase age. An increase in the

number of prior ED visits in the previous year was associated with an increased odds of revisiting

with a worse CTAS score (AOR 1.35 95% CI 1.29, 1.41 for 2 visits, AOR 1.82 95% CI 1.74, 1.91 for 3+

visits) but children who frequented the ED for low acuity visits had a lower odds of worsening CTAS

score (AOR 0.42 95% CI 0.39, 0.45 for 3+ low acuity visits). Daytime or evening presentation to the

ED on the index visit was associated with an 82% and 24% increased odds of a worse CTAS score,

respectively. The AIC was 229513 with a c-statistic of 0.804 when including immigrant status, age,

sex, deprivation index, low acuity and all cause ED visits in the preceding year, CTAS at the index

visit, chief complaint, shift time, shift day, pediatric ED hospital volume, and hospital type.

Table 17. Unadjusted and adjusted logistic regressions with odds ratios of ED revisits leading to worse CTAS score according to patient and hospital characteristics (n = 249648)

Unadjusted OR (95% CI)

p-value Adjusted OR (95% CI)*†

p-value

Immigrant Status

Non-immigrant Reference - Reference - Longer-term immigrant 1.03 (1.00, 1.07) 0.069 1.01 (0.97, 1.05) 0.744 Recent immigrant 1.06 (1.02, 1.11) 0.009 0.99 (0.94, 1.04) 0.638

Patient Characteristics

Age, years

0 - <1 1.48 (1.42, 1..53) <.001 2.36 (2.26, 2.47) <.001

1 - 2 1.50 (1.48, 1.55) <.001 1.82 (1.75, 1.90) <.001

3 - 6 1.33 (1.28, 1.38) <.001 1.40 (1.34, 1.46) <.001

7 - 10 1.12 (1.08, 1.17) <.001 1.15 (1.10, 1.20) <.001

11 - 14 0.98 (0.94, 1.01) 0.194 1.03 (0.99, 1.08) 0.143

15 - 17 Reference - Reference -

Sex

F 0.99 (0.97, 1.01) 0.436 0.95 (0.93, 0.97) <.001

M Reference - Reference -

Deprivation quintile

1 (least deprived) Reference - Reference -

2 0.96 (0.93, 0.99) 0.007 0.95 (0.92, 0.98) 0.004

3 1.01 (0.98, 1.04) 0.481 0.97 (0.93, 1.00) 0.058

4 1.05 (1.02, 1.09) 0.004 0.95 (0.92, 0.98) 0.006

5 (most deprived) 1.11 (1.08, 1.14) <.001 0.98 (0.94, 1.01) 0.198

ED visits in previous year (#),

0 Reference - Reference -

1 1.11 (1.08, 1.14) <.001 1.17 (1.13, 1.21) 0.635

2 1.19 (1.15, 1.23) <.001 1.35 (1.29, 1.41) <.001

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3+ 1.31 (1.28, 1.35) <.001 1.82 (1.74, 1.91) <.001

Low acuity ED visits in previous year (#)

0 Reference - Reference -

1 1.07 (1.04, 1.10) <.001 0.72 (0.69, 0.74) <.001

2 1.13 (1.08, 1.18) <.001 0.56 (0.53, 0.60) <.001

3+ 1.14 (1.08, 1.20) <.001 0.42 (0.39, 0.45) <.001

ED visit characteristics

CTAS

1 - 2 n/a n/a n/a <.001

3 0.21 (0.21, 0.22) <.001 0.12 (0.12, 0.13) <.001

4 – 5 Reference - Reference -

Chief complaint index visit

Injury/trauma Reference - Reference -

Neurologic 1.09 (1.02, 1.16) <.001 4.06 (3.76, 4.40) <.001

Skin problems 1.48 (1.40, 1.55) 0.011 1.48 (1.40, 1.57) <.001

Administrative issue 1.62 (1.50, 1.75) <.001 1.78 (1.63, 1.94) <.001

General symptoms 1.65 (1.54, 1.77) <.001 2.62 (2.41, 2.84) <.001

Other 1.36 (1.31, 1.41) <.001 2.46 (2.35, 2.56) <.001

Mental health 1.43 (1.32, 1.55) <.001 4.34 (3.94, 4.78) <.001

Newborn 0.91 (0.82, 0.99) 0.034 2.40 (2.28, 2.51) <.001

Infectious problems 1.68 (1.62, 1.75) <.001 2.39 (2.28, 2.51) <.001

Cancer 1.46 (1.24, 1.73) <.001 4.58 (3.74, 5.60) <.001

Gastrointestinal 1.04 (1.00, 1.08) 0.053 2.15 (2.06, 2.24) <.001

Asthma 1.51 (1.43, 1.60) <.001 4.31 (4.03, 4.62) <.001

URTI/Otitis media 1.87 (1.81, 1.92) <.001 2.56 (2.46, 2.65) <.001

Fever 1.25 (1.19, 1.32) <.001 2.12 (1.99, 2.26) <.001

Shift time

Night Reference - Reference -

Day 1.29 (1.25, 1.33) <.001 1.24 (1.20, 1.29) <.001

Evening 1.18 (1.15, 1.20) <.001 1.06 (1.04, 1.09) <.001

Shift day

Weekday Reference - Reference -

Weekend/holiday 1.11 (1.08, 1.13) <.001 1.06 (1.04, 1.09) <.001

Hospital Type

Community 0.81 (0.78, 0.82) <.001 1.22 (1.18, 1.27) <.001

Pediatric Reference - Reference -

Small 0.80 (0.75, 0.85) <.001 0.66 (0.61, 0.71) <.001

Teaching 0.91 (0.87, 0.94) <.001 1.48 (1.41, 1.56) <.001

Annual hospital pediatric ED volume

High (>16,000) Reference - Reference -

Low (<10,000) 0.90 (0.87, 0.92) <.001 0.78 (0.75, 0.81) <.001

Medium (10,000-16,000) 0.89 (0.86, 0.91) <.001 1.02 (0.99, 1.06) 0.229 *= adjusted for age, sex, deprivation index, low acuity ED visits in past year, ED visits in past year, CTAS score, chief complaint, shift time, shift day, hospital type, hospital volume. †Missing = 314

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4.7.2 Association of immigrant category, native language, official language of country of birth, and

region of origin with revisits leading to worse CTAS score

The association between immigration characteristics and revisits leading to worse CTAS score are

displayed in Table 18. Overall, of the 7.5% of visits the led to a return visits, approximately 19% of

immigrants returned to the ED with a worse CTAS score (range 18.8% to 19.4%) and there was no

significant difference based on immigration category, native tongue, and country’s official

languages. Children from Eastern and Central Europe, Middle and North Africa, and industrialized

nations had the lowest proportion of revisits with a worse CTAS score (17.7%, 18.2%, 18.5%,

respectively).

Table 18. Revisits to an ED leading to a worse CTAS score on the revisit based on immigrant characteristics (n = 38956)

Immigration characteristics Longer-term immigrant,

n (%)

Recent immigrant n (%)

Total n (%)

p-value*

Immigration Category Economic 1670 18.8 1007 18.6 2677 18.8 0.310 Family 2299 19.1 962 20.2 3261 19.4 Refugee 896 19.1 630 19.8 1526 19.4

Native tongue English 843 17.3 234 18.0 1077 14.4 0.731 French 20 18.8 22 22.4 42 20.6 No English or French 4002 19.0 2343 19.6 6345 19.2

Country with official language English 763 19.4 37 18.0 1000 19.6 0.149 French 84 20.8 84 23.1 168 21.9 No English or French 4018 18.9 2278 19.5 6296 19.1

Region of origin 0.026 Central and Eastern Europe 373 18.1 193 16.6 566 17.7 East Asia 938 19.0 521 17.0 1469 19.1 Eastern and Southern Africa 319 20.5 189 19.4 508 21.3 Industrialized 663 18.0 310 22.8 973 18.5 Latin American and Caribbean 952 19.7 331 19.4 1283 19.7 Middle East and North Africa 404 18.1 271 18.2 675 18.2 South Asia 1136 19.4 716 19.7 1852 19.6 West and Central Africa 80 18.3 67 20.4 147 19.2 *= Chi-squared test

The logistic regression models for ED revisits leading to a worse CTAS score are displayed in Table

19. The adjusted model was adjusted for age, sex, deprivation index, ED use in the previous year,

low acuity ED use in the previous year, CTAS score at the index visit, chief complaint, shift time, shift

day, hospital pediatric ED volume, hospital type, immigration category, native tongue, region of

origin, and immigration timing. No differences in the odds of a worse CTAS score at the revisit were

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observed between immigrant classes. Similarly, no differences were observed between those with

and without English as a native tongue though non-English/French speakers trended towards a

protective effect (AOR 0.91, 95% CI 0.82, 1.00). There was heterogeneity in the odds of revisiting

the ED with a worse CTAS score depending on the region of origin. Patients from South Asia had a

significantly higher odds of returning with a worse CTAS score (AOR 1.13 95% CI 1.02, 1.25) and

those from Eastern and Southern Africa trended toward an increased odds of revisit with a worse

CTAS score (AOR 1.15, 95% CCI 1.00, 1.33). Finally, there were no differences in the odds of a worse

CTAS score at the revisit based on recency of immigration.

Table 19. Unadjusted and adjusted odds ratios of ED revisits leading to a worse CTAS score according to immigration characteristics

Unadjusted OR (95% CI)

p-value Adjusted OR (95% CI)*†

p-value

Immigration Characteristics n = 38956

Immigration Category

Economic Reference - Reference - Family 1.04 (0.98, 1.10) 0.149 0.95 (0.89, 1.02) 0.144 Refugee 1.04 (0.97, 1.11) 0.279 0.98 (0.89, 1.06) 0.575

Native Tongue English Reference - Reference -

French 1.12 (0.79, 1.58) 0.537 1.03 (0.68, 1.54) 0.648

No English or French 1.02 (0.95, 1.10) 0.550 0.91 (0.82, 1.00) 0.062

Region of origin

Central and Eastern Europe 0.95 (0.85, 1.06) 0.360 0.92 (0.81, 1.05) 0.236

East Asia 1.04 (0.95, 1.14) 0.354 0.99 (0.89, 1.10) 0.812

Eastern and Southern Africa 1.19 (1.06, 1.34) 0.004 1.15 (1.00, 1.33) 0.057

Industrialized Reference - Reference -

Latin American and Caribbean 1.08 (0.98, 1.18) 0.108 0.97 (0.87, 1.08) 0.593

Middle East and North Africa 0.98 (0.88, 1.09) 0.696 0.96 (0.85, 1.09) 0.524

South Asia 1.07 (0.98, 1.17) 0.110 1.13 (1.02, 1.25) 0.022

West and Central Africa 1.05 (0.86, 1.27) 0.638 1.00 (0.79, 1.26) 0.984

Immigration Timing Recent 1.03 (0.98, 1.08) 0.300 0.97 (0.91, 1.04) 0.408 Longer-term Reference - Reference - *=Adjusted for age, sex, deprivation quintile, ED use in previous year, low acuity ED use in previous year, CTAS score at index visit, chief complaint, shift time, shift day, hospital pediatric ED volume, hospital type, immigration category, native tongue, region of origin, immigration time (longer-term/recent) † Missing 1398 patients in adjusted models

4.7.3 Assessment of multi-collinearity of independent variables for revisits leading to worse CTAS

score on the revisit

Table 20 shows the variance inflation factor and tolerance for the independent variables. As with

the previous outcome measures, the Ontario Marginalization Index deprivation score was correlated

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with neighbourhood income quintile with a variance inflation factors of 2.4 and tolerance of 0.4 and

the deprivation index was chosen as a proxy for socioeconomic status given it’s stability over time

relative to neighbourhood income quintile [70]. Native tongue and language of country of origin

were also collinear. Language of country of origin was excluded from the final models.

Table 20. Tolerance and variance inflation factors for independent variables for ED revisits leading to worse CTAS score on the revisit

Variable Tolerance VIF

Immigrant status 0.947 1.056 Age 0.913 1.095 Sex 0.997 1.003 CTAS score at visit 0.949 1.054 Chief complaint at visit 0.960 1.041 Hospital type 0.898 1.114 Marginalization index – material deprivation 0.411 2.394 Shift day 0.996 1.004 Neighbourhood income quintile 0.418 2.429 ED visits in previous 1 year 0.648 1.548 Shift time 0.987 1.013 Annual hospital pediatric volume 0.915 1.093 Low acuity ED visits in previous 1 year 0.644 1.554 Native tongue 0.290 3.449 Language of country of origin 0.286 3.503 Region of origin 0.944 1.062

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5.0 Discussion

5.1 Key Findings

Immigrant Status:

Baseline demographic and visit characteristics of immigrants who use an ED are different compared

with those of non-immigrants.

Overall, index visits and revisits by recent immigrants were largely from younger and lower

socioeconomic status children. This is in contrast to index visits and revisits from non-immigrants

where the distribution of patients between age groups and socioeconomic status quintiles was more

even. This is the first study to report baseline demographic characteristics of immigrant versus non-

immigrant children who use an ED for all causes in North America.

Patterns of ED use differ by immigrant status. Our findings suggest that non-immigrants have more

frequent ED use in the preceding year both for low acuity and all cause visits. Javier et al. have also

shown this pattern of use in pediatric immigrants versus non-immigrants diagnosed with asthma in

the US [75]. Similarly, Wen et al. and Tarraf et al. have shown all-cause ED use by adult non-

immigrants was higher compared with immigrants in Ontario and the US, respectively [50, 51]. This

may be reflective of barriers to ED use by immigrants or conversely, it may represent better access

to primary care for these individuals.

The acuity of presentation at an ED visit differs by immigrant status. The current study has shown

immigrants have a worse acuity score (i.e. more emergent) upon presentation to an ED. This is in

contrast to others in both the US and Canada [76, 77] who have shown a lower acuity by limited-

English proficient patients at ED visits. Differences may exist in acuity of presentation within

subgroups of immigrants (i.e. language proficiency) that were not distinguished in the current study.

The association between acuity score and immigration status in this study may be reflective of a

number of factors. Immigrants may wait longer and therefore present sicker prior to seeking help in

the emergency room. Disease burden, in particular with infectious diseases or malnutrition, may be

higher in immigrants so that when they present, they appear sicker compared with native-born.

Alternatively, expression or interpretation of disease severity may be different based on culture or

language such that immigrants express more signs of distress or pain at triage or the triage nurse

interprets a patient as sicker due to communication barriers.

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The main reason for the ED index visit differed by immigrant status. A much larger proportion

(41.2%) of non-immigrants presented with injury or trauma as the visit reason whereas only 32.6%

of recent immigrants presented with injury or trauma. Though not the primary focus of this study,

this finding highlights the importance of understanding the burden of illness in immigrant

populations as they appear to differ from that of Canadian-born children.

There is no evidence to report to report an independent effect of immigration status on 7-day ED

revisits or revisit outcomes including revisits leading to admission and revisits leading to a worse

CTAS score.

Overall, the proportion of 7-day ED revisits was higher in recent immigrants (8.0%) compared with

longer-term and non-immigrants (7.5%). When biologically and clinically important covariates

related to the patient, visit, and hospital were included in the adjusted model, the observed

relationship between the exposure groups disappeared. The greatest patient level predictors for

revisiting an ED were age, socioeconomic status, and propensity to use an ED in the preceding year.

These predictors of ED revisits have previously been reported in the literature [10, 41, 43, 44]. The

younger age and lower socioeconomic status of immigrant children largely explain the observed

differences in the unadjusted revisits by immigrant status. To our knowledge, this is the first study

to report on immigrant status and return ED visits in North America.

The proportion of ED visits leading to a return visit in the current study falls within the range of

previously reported rates for pediatric ED revisits across North America. However, direct

comparison with previously reported revisit rates is difficult because of the variability in the

definition of time to return visits [27, 37, 41, 43, 66, 78-81].

The revisit leading to admission to hospital rate for the total population was 12.7%. The overall rate

for patients initially seen and discharged from the ED and who then return to be admitted was

0.96%. The admission rate on the revisit in the current study is comparable to rates reported in the

literature [26, 29, 39, 41, 66, 78]. Specifically, the mean return-to-admission rate reported in 2007

Pediatric Emergency Care Applied Research Network (a national consortium of US children’s

hospitals) was 1.3% [82].

This study identified a significant association between immigrant status and revisits leading to

admission to hospital. Only 12.5% of non-immigrant revisits led to admission, whereas 13.9% of

longer-term immigrants and 14.8% of recent immigrants were admitted to hospital on the revisit. In

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the adjusted models, these differences disappeared. Across all patients, higher acuity of illness,

likely representing progression of disease, was the main factor associated to admission to hospital at

the revisit. Higher rates of admission to hospital in recent immigrants could largely be explained by

the increased odds of being admitted to hospital with younger age combined with the relatively

higher proportion of young children in the recent and longer-term immigrant groups. Other

significant factors predicting admission to hospital at the revisit included shift time, shift day, and

hospital type. These factors have all been previously reported as contributors to admission on a

revisit, though not consistently in the literature [29, 39]. Material deprivation did not appear to play

a significant role in the odds of admission on the revisit. There is limited previous literature on

immigrants and admission to hospital. One study from Spain showed immigrant women are more

likely to be admitted to hospital compared with Spanish born [83].

We identified a statistically significant higher odds of revisiting the ED and having a worse CTAS

score in recent and longer-term immigrants compared with non-immigrants. As with the other

outcome measures, these differences disappeared when adjusting for other biologically and

clinically important covariates. Age was by far the biggest predictor of returning to the ED with a

worse CTAS score, especially when comparing young infants to teenagers (AOR 2.36 95% CI 2.26,

2.47). Given the differences in age distribution between immigrants and non-immigrants, age can in

part, explain differences in the unadjusted and adjusted odds for returning to the ED with a worse

CTAS score. To our knowledge, this is the first study to report on acuity scores at a return visit for

immigrant children.

The lack of observed difference between immigrant status and the three main outcome measures in

adjusted models may be explained by a number of factors. First, it is possible that as Canadians, we

are providing ‘adequate’ accessibility and quality of care for immigrants such that no differences in

ED revisits exist. Others in have also shown no difference in ED use by immigrants in Italy [84].

Selective migration for healthier, more motivated, and resourceful individuals may have contributed

to our findings. More likely though, the heterogeneity within the pooled immigrant groups may

have masked some expected outcomes for this population. Some patients within the immigrant

groups may have been more vulnerable and likely to have particular worse outcome measures

whereas other subgroups may have had protective factors that reduced the odds of worse outcome

measures. This heterogeneity in the immigrant population may also explain some of the variability

in ED use by immigrants reported in the literature.

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Immigrant Class:

There is insufficient evidence to report an independent effect of immigration class on 7-day ED

revisits, revisits leading to admission, or revisits leading to a worse CTAS score.

The relative proportion of ED index visits by immigrants was 38.2% for Economic class, 41.9% for

Family class, and 19.9% for Refugee class. These proportions are markedly different from the

expected proportions of immigrants visits based on their distribution in the Ontario population.

Refugee and Family class immigrants make up a disproportionately large fraction of ED index visits.

Though not a primary objective of this study, this finding highlights the need for further review of

accessibility to primary and urgent care for these more vulnerable groups of immigrants in Ontario.

In comparing 7-day ED revisits by immigration category, Family class and Refugee class immigrants

had a significantly higher proportion of 7-day ED revisits compared with Economic class immigrants

though when adjusted for other covariates, these differences were no longer significant. We did not

evaluate the relative proportions of immigrants within each class by each demographic variable,

however, it is possible that Family class and Refugee class immigrants had larger proportions of

young patients using the ED for the index visit. Thus, it is possible that differences in age

distribution between classes accounts for the observed differences in the unadjusted models.

Similarly, socioeconomic status may have been a contributing factor.

In this study, we reported a significantly higher odds of being admitted on the revisit in Family Class

patients, especially in those recently immigrated, compared with Economic and Refugee Classes.

This was no longer statistically significant in the adjusted models. In addition, in comparing

immigrant classes, we found no differences in the odds of returning to the ED with a worse CTAS

score compared with the index visit in the adjusted models.

The lack of observed difference between immigrant classes may indicate that services and policies

are in place currently that allow for quality care to be delivered to the various classes equally. More

specifically, existing targeted interventions and heightened awareness of vulnerable groups by care

providers may be sufficient to mitigate potential poor interactions that lead to hospital admission.

Immigrant Language:

These data support an independent effect of language on 7-day ED revisits and 7-day ED revisits

leading to admission but not for 7-day ED revisits leading to a worse CTAS score.

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The time demands on the health care provider in interactions where language barriers exist can

affect how well health information can be conveyed to the patient. Such interactions take time, and

are particularly challenging in the ED setting where providers are under pressure to see families

efficiently. Language barriers undermine the empathy conveyed by the physician and impair the

ability to establish rapport, explain discharge instructions, and appreciate illness impact on the

family. Likewise, language barriers test a family’s ability to convey their health concerns to the

provider, curtail the empathy experienced by the family, and reduce understanding about the

treating team’s assessment and management plan.

In this study, non-English or French speaking (based on native tongue) immigrants had significantly

higher odds of revisiting the ED compared with English or French speaking immigrants. Similarly, if

the patient came from a country where English or French were not an official languages, the odds of

revisit was higher. After adjusting for other covariates, these differences persisted with a 5% higher

odds of revisiting an ED in the non-English or French speaking patients. To our knowledge, this is the

first report of the impact of language on pediatric patients’ revisits to the ED. It highlights that

language barriers contribute to increased health services use and may be an area in need of

targeted interventions for improved patient safety.

Non-English or French speakers were less likely to be admitted to hospital on the revisit compared

with those who were born in countries where English or French are official languages or where the

native tongue is English or French. These differences were still significant after adjusting for other

covariates. Goldman et al. [39] reported no association between language and return visits leading

to admission in another recent study at a Canadian tertiary care centre. Our findings and those of

Goldman et al., are in contrast to Gallagher et al. [29] who reported a 43% higher odds of admission

on the revisit for patients with limited English proficiency in the US. Prior work in pediatric patients

has demonstrated an association between language barriers leading to higher rates of admission to

hospital at an index ED visit. In their study, Rogers et al. reported a 22% admission rate in limited

English proficient patients compared with 13% of English speakers [76]. It is possible in our study

that patients who did not speak a Canadian language were admitted more often on the index visit

and therefore had a reduced likelihood of a revisit, or revisit leading to admission hospital (i.e. the

sicker patients were already admitted). Unfortunately, this analysis was outside of the scope of the

current study and therefore these results are not presented.

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After adjustment for covariates, there was no statistically significant association between language

and revisiting the ED with a worse CTAS score. Galllagher et al. reported a better (less emergent)

acuity score both at the index visit and on the return visit in limited-English proficient patients [29].

Conversely, Rogers et al. [76] evaluated whether limited English proficiency patients had different

acuity status in a pediatric ED and found compared with English-speaking visits, limited English

proficiency visits were more likely to be triaged as high acuity. This was particularly evident in

moderate acuity patients. Understanding the causative factors contributing to these different study

results would be useful for further study on language barriers in the ED.

Immigrant Characteristics: Region of Origin

These data support an independent effect of region of origin on 7-day ED revisits and revisits leading

to admission, but not on revisits leading to a worse CTAS score.

There was regional variability in the odds of revisiting an ED. As hypothesized, patients from

industrialized regions had the lowest proportion of index visits leading to a revisit (7.3%). Children

from East and South Asia, as well as from Eastern and Southern Africa had the highest proportion of

patients revisit an ED. After adjusting for covariates, patients from East Asia continued to have an

increased, albeit small, odds of revisiting an ED compared with those from industrialized nations.

South Asian patients also had an increased odds of 7-day ED revisit though this did not reach

statistical significance (p = 0.051). There may be accessibility, cultural, or perceived health status

differences in these groups that may explain the observed differences.

Patients from South Asia and Western and Central Africa had a 23% and 41% higher odds of being

admitted on the revisit compared with patients from industrialized nations. Patients from Central

and Eastern Europe had a lower odds of admission compared with those from industrialized nations

(AOR 0.84 95% CI 0.73, 0.97). Differences in culture, social supports, and perceived health status

may also explain this finding.

We observed little regional differences in the odds of returning with a worse CTAS score at the

revisit when comparing the various regions of origin and visits from patients emigrating from

industrialized nations. It is possible that the standardized nature of the CTAS scoring system reduces

some of the variability between patient groups. Also, this suggests that the interaction at the index

visit is of decent enough quality so that patients from different regions of origin do not present

‘sicker’ at the revisit.

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Overall, there is a lot of heterogeneity across groups and subgroups. Some of this heterogeneity

was reduced with model specification though there continue to be some unexplained variability.

This may result from unmeasured characteristics, but also from residual variability between

countries within migrant subgroups. We may have uneven representation of some countries with

the UNICEF world regions which may affect effect estimates. However, this also reflects the diversity

in immigration patterns from receiving countries. Other studies on pediatric health outcomes and

health systems interaction have also reported certain sub-populations from Asia and Africa are at

risk for worse health outcomes and interactions [85, 86].

5.2 Strengths of Study

In an era of quality improvement and patient safety, policy makers and health care providers are

interested in improving the delivery of care, in particular, to vulnerable populations. The large and

growing pediatric immigrant population in Canada has different drivers of health system use and

interactions that need better understanding in order to effect change. This study is the first to

provide a glimpse into understanding pediatric immigrant ED use and safety in Canada and can serve

as a stimulus for further study of this population.

A major strength of this study is that is provides a very large sample size with little selection bias.

Most landed immigrant children living in Ontario are captured through their OHIP coverage when

they visit an Ontario ED. Through the linked databases, we were able to ascertain a number of

important, validated clinical and demographic data that are key to understanding ED revisits.

Immigrant data is based on official immigration documents through a government-run

computerized immigration database. For data to be entered, individuals are required, by law, to

have notarized copies of personal documentation, including country of birth and country of

emigration. These data are relatively accurate and complete, especially in comparison to US data

that relies heavily on self-reported ethnicity or race information.

Longitudinal changes in a patients socio-demographic characteristics were accounted for over time

and measured at the time of the visit. For example, each index visit measured socioeconomic data

based on the most current postal code. This is important, especially for immigrants, who arrive in

Canada and may have a shifting socioeconomic status based on their duration of residence. Thus,

residential mobility after first arrival in Canada was accounted for.

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5.3 Limitations

There are a number of limitations to this study. First, given the cross-sectional design, causality

cannot be inferred between tested associations. There may be residual confounding from unknown

and unmeasured covariates such as individual level income (rather than census based income or

deprivation from the patient’s postal code), social supports, or culture. The current study only

included pediatric patients living in CMA’s of Ontario and therefore these results may not be

generalizable to children outside of these regions. For our analysis, we used logistic regression to

model our outcomes. Traditionally, such modelling tends to overestimate the relative risk,

especially when the outcome is common. Recognizing this, we report odds ratios rather than

relative risks and our main outcome measure, the odds of revisit, was relatively rare (~7 to 8%).

Thus, the impact of this limitation of logistic regression is likely small for our study.

We used complete case analysis to account for missing data. While this methodology may introduce

some bias, especially if data are not missing completely at random, the proportion of missing data

was very low (< 5% for deprivation index and <0.001 for discharge disposition on the revisit) and was

equally distributed between exposure groups. The impact of this method of handling missing data

on our results was likely negligible.

Our measures of language were imperfect, based on self-reported native language and the official

languages of the country of birth. These measures do not assess English or French language

proficiency, thereby diluting the measured effect of language on ED revisits and their outcomes.

Thus, the measured effects of language may underestimate the true impact of limited language

proficiency on ED revisit outcomes.

There are a number of limitations with the immigration data available. First, linkage of the

Permanent Resident Data System to other health and demographic administrative databases is not

perfect with approximately 14% of immigrants unlinked and therefore potentially misclassified as

non-immigrants. Second, patients (mothers) who landed in Canada prior to 1985 were potentially

misclassified as a non-immigrants. This limitation would be relevant only to a few patients. Women

of childbearing age who then had a child in Canada who visited the ED would have been in Canada

for at least 17 years or have spent a good part of their childhood in a Canadian setting. This would

bias the results towards the null hypothesis. The Landed Immigrant Data System does not capture

temporary or undocumented immigrants who may represent some of the most at risk population

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for poor health system interactions and outcomes. This limitation may bias our outcomes towards

failing to reject our null hypothesis. Similarly, immigrants landing in other provinces and then

moving to Ontario after arrival would be classified as non-immigrants. There may be bias in the

classification of immigrant status by region of origin with differential linkage rates across immigrant

country of origin. For example, East Asian linkage rates are worse than other regions, potentially

misclassifying some of these individuals as non-immigrants (personal communication). Finally, the

immigrant data is a snapshot at the time of landing and does not necessarily equate to the date of

arrival in Canada. Therefore, immigrants who were classified as ‘recent’ may have actually been in

Canada for more than five years. This would make the effect of recency of immigration an

underestimate. Similarly, the data does not detail acculturation time in a Western or industrialized

country prior to arrival in Canada. For example, a patient may have been born in India but spent ten

years in the United Kingdom prior to immigrating to Canada. This may underestimate the effect of

immigration, especially for outcome measures involving region of origin.

Our definition of ‘immigrant’ has some limitations. Defining an immigrant was based on either the

child’s or mother’s immigration status and linked through the MOMBABY database at ICES. No

information about paternal immigrant status was available. This unmeasured variable could

certainly explain some of the variability in the data. Depending on the father’s immigration

information, the culture of the family (patriarchal or matriarchal), and the influence of the primary

care giver, interaction with the health system may fluctuate.

For the current study, we had no information available on primary care access or availability. We

used low acuity revisits as a proxy for poor access to primary care, but this measure is not ideal. The

validity of using OHIP billing codes for pediatric primary care rostering is poor, especially in an

immigrant population where many immigrants may use community health centres for care [87].

The visits to community health centres would not necessarily be captured through linkage with OHIP

billings, precluding accurate identification of patients with a regular place for primary care.

5.4 Future directions

Patient and visit factors identified in this study as being associated with 7-day ED revisits present an

opportunity for future studies on targeted interventions. The observed associations between

covariates and outcomes highlights important explanatory variables, but given the strength of the

observed relationships, it also reveals areas for future research. We found young children, families

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with low socioeconomic status, children with frequent low acuity and all cause visits to be more

likely to revisit an ED. Going forward, we can evaluate what interactions may occur in these events

and what preventative or follow-up measures can be put in place to better serve these populations.

Further study could also evaluate the appropriateness of these revisits and admissions. For young

and low socioeconomic status children, we can further study what better systems can be put in

place to improve meeting their health needs.

Future studies need to determine if differences (or lack thereof for some outcome measures) are

based on selective migration or due to differential exposures within the receiving environment.

Understanding which risk factors may be modifiable for improved health system interactions will

help to develop targeted strategies to improve care for immigrants.

Immigrants to Ontario are a heterogeneous population. The low effect estimates may largely be

explained by having combined immigrant groups from different regions each potentially

contributing to the outcomes in different directions. Future studies should focus on better

distinction between subgroups of immigrants by region and country of origin. This can help to give

us a better understanding of specific health needs of the various populations in Ontario.

This study focused on immigrant 7-day ED revisits – a measure of quality and safety resulting from

an interaction in the ED. Studies on immigrant ED use, accessibility to care, diagnoses, and temporal

trends in health system use and quality would be invaluable to developing a strategy to improve

delivery of care to immigrant children and their families.

In Canada, we have a large proportion of temporary residents [4] and know little about how they

use the health system in Ontario. This population may have some similar characteristics to

permanent residents but there may also be some important differences. We need to better

understand characteristics of temporary residents and how they affect health system use and

interactions.

We identified that language barriers have an independent effect on ED revisits. Next steps to

address this result could be to evaluate the role of translator services in the ED on mitigating some

of the barriers faced by immigrants in this setting. A US study on pediatrician interpreter use

showed that in states where premiums were paid to physicians for using an interpreter, uptake of

interpreter services was more than two-fold compared with states with no reimbursement for

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interpreter use [88]. This finding has important implications for consideration of enhanced fee

codes for translator service use by pediatricians in Canada.

5.5 Implications

This study on 7-day ED revisits and immigrants has important implications and opportunities for

knowledge translation to policy makers and care providers. The key findings of this study will be

shared with Citizenship and Immigration Canada, the Ministry of Health and Long-Term Care of

Ontario, the Pediatric Emergency Research Canada group, and ED directors across Canada as they

work to improve the delivery of ED care to new Canadian residents.

Immigration status does not appear to independently influence ED revisits. This is an important

‘negative’ finding. Traditionally, immigrants, as a whole, are considered a vulnerable population.

This suggests that our current system, while not perfect, is adequate in providing care in the ED such

that revisit rates are not higher among immigrants. Conversely, poor English or French language

ability appears to increase the odds of revisiting an ED. Similarly, patients from Asian countries have

a higher odds of revisiting an ED and being admitted on the revisit. These suggest a potential poor

health system interaction where language or culture may impact the quality of care delivered.

These language data highlight the need to evaluate improved professional language service

availability within an ED. Patients without English or French as a first language may benefit from

translator services being offered at all visits to explain all assessment and management decisions

and discharge instructions. As this may be time consuming, consideration should be given to

enhanced fee codes for use of translator services with patients who may need them. Currently,

there is no remuneration for the time it takes to take a patient history or give discharge instructions

using a translator. Incentivizing use of translator services may increase uptake and reduce barriers

to quality care for these patients. This information should be shared with the Ministry of Health and

Long-Term Care of Ontario as an avenue to potentially explore this strategy. Finally, for patients

who do not speak English or French, multi-language, culturally sensitive, written discharge

information about common childhood complaints should be made available to care providers to

distribute to appropriate patients and enhance the care provided. These findings should be

conveyed to ED directors as it may help improve revisit outcomes for this subgroup of patients.

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The regional variation in outcomes also highlights potential deficiencies in cultural competency

among care providers. Cultural competency training could be warranted for care providers and

medical trainees and this information should be disseminated to ED directors.

Finally, use of the Landed Immigrant Data System linkage with other health administrative and

demographic databases to explore health system use is relatively new in Canada. Studies like the

current one can demonstrate the importance of these linkages in understanding delivery of care to

immigrants. Specifically, we demonstrated language proficiency is related to healthcare quality and

safety. This finding could drive post-migration and clinical care programs for new immigrants.

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30. Sauvin, G., et al., Unscheduled return visits to the emergency department: consequences for triage. Acad Emerg Med, 2013. 20(1): p. 33-9.

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32. Geirsson, O.P., et al., Risk of repeat visits, hospitalisation and death after uncompleted and completed visits to the emergency department: a prospective observation study. Emerg Med J, 2013. 30(8): p. 662-8.

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34. Depiero, A.D., D.W. Ochsenschlager, and J.M. Chamberlain, Analysis of pediatric hospitalizations after emergency department release as a quality improvement tool. Ann Emerg Med, 2002. 39(2): p. 159-63.

35. Martin-Gill, C. and R.C. Reiser, Risk factors for 72-hour admission to the ED. Am J Emerg Med, 2004. 22(6): p. 448-53.

36. Goldman, R.D., M. Ong, and A. Macpherson, Unscheduled return visits to the pediatric emergency department-one-year experience. Pediatr Emerg Care, 2006. 22(8): p. 545-9.

37. Alessandrini, E.A., et al., Return visits to a pediatric emergency department. Pediatr Emerg Care, 2004. 20(3): p. 166-71.

38. Steiner, C., M. Barrett, and K. Hunter, Hospital Readmissions and Multiple Emergency Department Visits, in Selected States, 2006-2007: Statistical Brief #90, in Healthcare Cost and Utilization Project (HCUP) Statistical Briefs. 2006: Rockville (MD).

39. Goldman, R.D., A. Kapoor, and S. Mehta, Children admitted to the hospital after returning to the emergency department within 72 hours. Pediatr Emerg Care, 2011. 27(9): p. 808-11.

40. Jacobstein, C.R., et al., Unscheduled revisits to a pediatric emergency department: risk factors for children with fever or infection-related complaints. Pediatr Emerg Care, 2005. 21(12): p. 816-21.

41. Freedman, S.B., et al., Emergency department revisits in children with gastroenteritis. J Pediatr Gastroenterol Nutr, 2013. 57(5): p. 612-8.

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42. Costabel, S., et al., Return visits to the Paediatric Emergency Department: first analysis in Italy. J Prev Med Hyg, 2008. 49(4): p. 142-7.

43. Dy, C.J., et al., Socioeconomic Factors are Associated With Frequency of Repeat Emergency Department Visits for Pediatric Closed Fractures. J Pediatr Orthop, 2014.

44. Walsh-Kelly, C.M., et al., Emergency department revisits for pediatric acute asthma exacerbations: association of factors identified in an emergency department asthma tracking system. Pediatr Emerg Care, 2008. 24(8): p. 505-10.

45. Mahmoud, I., et al., Satisfaction with emergency department service among non-English-speaking background patients. Emerg Med Australas, 2014.

46. Carrasquillo, O., et al., Impact of language barriers on patient satisfaction in an emergency department. J Gen Intern Med, 1999. 14(2): p. 82-7.

47. Divi, C., et al., Language proficiency and adverse events in US hospitals: a pilot study. Int J Qual Health Care, 2007. 19(2): p. 60-7.

48. Goh, S.H., et al., Unplanned returns to the accident and emergency department--why do they come back? Ann Acad Med Singapore, 1996. 25(4): p. 541-6.

49. Mian, O. and R. Pong, Does better access to FPs decrease the likelihood of emergency department use? Results from the Primary Care Access Survey. Can Fam Physician, 2012. 58(11): p. e658-66.

50. Wen, S.W., V. Goel, and J.I. Williams, Utilization of health care services by immigrants and other ethnic/cultural groups in Ontario. Ethn Health, 1996. 1(1): p. 99-109.

51. Tarraf, W., W. Vega, and H.M. Gonzalez, Emergency Department Services Use Among Immigrant and Non-immigrant Groups in the United States. J Immigr Minor Health, 2013.

52. Vaughn, L.M. and F. Jacquez, Characteristics of newly immigrated, Spanish-speaking Latinos who use the pediatric emergency department: preliminary findings in a secondary migration city. Pediatr Emerg Care, 2012. 28(4): p. 345-50.

53. Davidovitch, N., et al., Immigrating to a universal health care system: utilization of hospital services by immigrants in Israel. Health Place, 2013. 20: p. 13-8.

54. Norredam, M., et al., Emergency room utilization in Copenhagen: a comparison of immigrant groups and Danish-born residents. Scand J Public Health, 2004. 32(1): p. 53-9.

55. Payne, N.R. and S.E. Puumala, Racial disparities in ordering laboratory and radiology tests for pediatric patients in the emergency department. Pediatr Emerg Care, 2013. 29(5): p. 598-606.

56. Bhatia, R. and P. Wallace, Experiences of refugees and asylum seekers in general practice: a qualitative study. BMC Fam Pract, 2007. 8: p. 48.

57. Smith, P.C., J.H. Brice, and J. Lee, The relationship between functional health literacy and adherence to emergency department discharge instructions among Spanish-speaking patients. J Natl Med Assoc, 2012. 104(11-12): p. 521-7.

58. Hampers, L.C., et al., Language barriers and resource utilization in a pediatric emergency department. Pediatrics, 1999. 103(6 Pt 1): p. 1253-6.

59. Flores, G., et al., Errors of medical interpretation and their potential clinical consequences: a comparison of professional versus ad hoc versus no interpreters. Ann Emerg Med, 2012. 60(5): p. 545-53.

60. ICES. Working with ICES data. 2014 October 3rd, 2014]; Available from: http://www.ices.on.ca/Data-and-Privacy/ICES-data/Working-with-ICES-Data.

61. CIHI, Data Quality Documentation, National Ambulatory Care Reporting System—Multi-Year Information. 2012, Canadian Institute for Health Information: Ottawa, ON.

62. CIHI, CIHI Data Quality Study of Emergency Department Visits for 2004-2005: Volume II of IV - Main Study Findings. 2008, Canadian Institute for Health Information: Ottawa, ON.

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63. ICES. MOMBABY Database - Institute for Clinical Evaluative Sciences Intranet. 2013 [cited 2013; Available from: https://ssl.ices.on.ca/dana-na/auth/url_default/welcome.cgi.

64. Canada, C.a.I. Institue of Clinical Evaluative Sciences Dataset Dictionary. 2013 [cited 2013; Available from: https://ssl.ices.on.ca/dataprog/Data%20Holdings/Population%20and%20Demographics/CIC/,DanaInfo=inside.ices.on.ca+Index.htm.

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66. Bardach, N.S., et al., Measuring hospital quality using pediatric readmission and revisit rates. Pediatrics, 2013. 132(3): p. 429-36.

67. Zimmerman, D.R., et al., Repeat pediatric visits to a general emergency department. Ann Emerg Med, 1996. 28(5): p. 467-73.

68. CIHI, All-Cause Readmission to Acute Care and Return to the Emergency Department. 2012: Ottawa, Ontario.

69. UNICEF. Unicef: Information by country and programme. 2014; Available from: http://www.unicef.org/infobycountry/.

70. Matheson, F.I., Dunn, J., Smith K.W.L, Moineddin, R., Glazier, R.H. , Ontario Marginalization Index user guide. Version 1.0. 2012, Centre for Research on Inner City Health.

71. StatsCan. Dissemination Area. 2012 October 9th, 2014]; Available from: http://www12.statcan.gc.ca/census-recensement/2011/ref/dict/geo021-eng.cfm.

72. Walker, E. and A.S. Nowacki, Understanding equivalence and noninferiority testing. J Gen Intern Med, 2011. 26(2): p. 192-6.

73. O'Brien, R., A caution regarding rules of thumb for Variance Inflation Factors. Quality & Quantity, 2007. 41: p. 673 - 690.

74. Hardin JW, H.J., Generalized estimating equations. 2003, Boca Raton, Fla: Chapman & Hall/CRC.

75. Javier, J.R., P.H. Wise, and F.S. Mendoza, The relationship of immigrant status with access, utilization, and health status for children with asthma. Ambul Pediatr, 2007. 7(6): p. 421-30.

76. Rogers, A.J., C.A. Delgado, and H.K. Simon, The effect of limited English proficiency on admission rates from a pediatric ED: stratification by triage acuity. Am J Emerg Med, 2004. 22(7): p. 534-6.

77. Goldman, R.D., P. Amin, and A. Macpherson, Language and length of stay in the pediatric emergency department. Pediatr Emerg Care, 2006. 22(9): p. 640-3.

78. Ali, A.B., et al., Early pediatric emergency department return visits: a prospective patient-centric assessment. Clin Pediatr (Phila), 2012. 51(7): p. 651-8.

79. Lee, E.K., et al., A clinical decision tool for predicting patient care characteristics: patients returning within 72 hours in the emergency department. AMIA Annu Symp Proc, 2012. 2012: p. 495-504.

80. Angoulvant, F., et al., Multiple health care visits related to a pediatric emergency visit for young children with common illnesses. Eur J Pediatr, 2013. 172(6): p. 797-802.

81. Goldman, R.D., et al., Impact of Follow-up Calls From the Pediatric Emergency Department on Return Visits Within 72 Hours: A Randomized Controlled Trial. Pediatr Emerg Care, 2014. 30(9): p. 613-6.

82. Alpern, E.R., et al., Recurrent and high-frequency use of the emergency department by pediatric patients. Acad Emerg Med, 2014. 21(4): p. 365-73.

83. Rue, M., et al., Emergency hospital services utilization in Lleida (Spain): A cross-sectional study of immigrant and Spanish-born populations. BMC Health Serv Res, 2008. 8: p. 81.

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84. Grassino, E.C., et al., Access to paediatric emergency departments in Italy: a comparison between immigrant and Italian patients. Ital J Pediatr, 2009. 35(1): p. 3.

85. Gagnon, A.J., et al., Migration to western industrialised countries and perinatal health: a systematic review. Soc Sci Med, 2009. 69(6): p. 934-46.

86. Gissler, M., et al., Stillbirths and infant deaths among migrants in industrialized countries. Acta Obstet Gynecol Scand, 2009. 88(2): p. 134-48.

87. Muggah, E., S. Dahrouge, and W. Hogg, Access to primary health care for immigrants: results of a patient survey conducted in 137 primary care practices in Ontario, Canada. BMC Fam Pract, 2012. 13: p. 128.

88. DeCamp, L.R., et al., Changes in language services use by US pediatricians. Pediatrics, 2013. 132(2): p. e396-406.

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Appendix A

Table IA. Census Metropolitan Areas in Ontario – 2006 Census

1. Toronto (535)

2. Ottawa (505)

3. Hamilton (537)

4. Kitchener-Cambridge-Waterloo (541)

5. London (555)

6. St. Catharines-Niagara (539)

7. Oshawa (532)

8. Windsor (559)

9. Barrie (568)

10. Greater Sudbury (580)

11. Kingston (521)

12. Brantford (543)

13. Thunder Bay (595)

14. Peterborough (529)

15. Guelph (550)

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Appendix B

Table IB. Country code, region, and language information

Code

Country Region Language

000 Country not stated Other Neither

001 United Kingdom and

Colonies

Industrialized English

002 England Industrialized English

003 British Citizen Industrialized English

004 British Overseas Citizen Industrialized English

005 British Dependent

Territories Citizen

Industrialized English

006 Northern Ireland Industrialized English

007 Scotland Industrialized English

008 Wales Industrialized English

009 Channel Islands Industrialized Neither

010 British National

Overseas

Industrialized English

011 Austria Industrialized Neither

012 Belgium Industrialized French

013 Luxembourg Industrialized French

014 Czechoslovakia Industrialized Neither

015 Czech Republic Industrialized Neither

016 Slovak Republic Industrialized Neither

017 Denmark Industrialized Neither

018 Estonia Industrialized Neither

019 Latvia Industrialized Neither

020 Lithuania Industrialized Neither

021 Finland Industrialized Neither

022 France Industrialized French

024 Germany, Federal

Republic of

Industrialized Neither

025 Greece Industrialized Neither

026 Hungary Industrialized Neither

027 Ireland, Republic of Industrialized English

028 Italy Industrialized Neither

030 Malta Industrialized Neither

031 Netherlands, The Industrialized Neither

032 Norway Industrialized Neither

033 Poland Industrialized Neither

034 Portugal Industrialized Neither

035 Azores Industrialized Neither

036 Madeira Industrialized Neither

037 Spain Industrialized Neither

039 Canary Islands Industrialized Neither

040 Sweden Industrialized Neither

041 Switzerland Industrialized French

042 Union of Soviet Socialist

Republics

Central and Eastern Europe and the Commonwealth of Independent States Neither

043 Croatia Central and Eastern Europe and the Commonwealth of Independent States Neither

044 Yugoslavia Central and Eastern Europe and the Commonwealth of Independent States Neither

045 Turkey Industrialized Neither

046 Germany, Democratic

Republic

Industrialized Neither

047 Slovenia Industrialized Neither

048 Bosnia-Hercegovina Central and Eastern Europe and the Commonwealth of Independent States Neither

049 Armenia Central and Eastern Europe and the Commonwealth of Independent States Neither

050 Azerbaijan Central and Eastern Europe and the Commonwealth of Independent States Neither

051 Belarus Central and Eastern Europe and the Commonwealth of Independent States Neither

052 Georgia Central and Eastern Europe and the Commonwealth of Independent States Neither

053 Kazakhstan Central and Eastern Europe and the Commonwealth of Independent States Neither

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72

054 Kyrgyzstan Central and Eastern Europe and the Commonwealth of Independent States Neither

055 Moldova Central and Eastern Europe and the Commonwealth of Independent States Neither

056 Russia Central and Eastern Europe and the Commonwealth of Independent States Neither

057 Tadjikistan Central and Eastern Europe and the Commonwealth of Independent States Neither

058 Turkmenistan Central and Eastern Europe and the Commonwealth of Independent States Neither

059 Ukraine Central and Eastern Europe and the Commonwealth of Independent States Neither

060 Uzbekistan Central and Eastern Europe and the Commonwealth of Independent States Neither

061 Serbia and Montenegro Central and Eastern Europe and the Commonwealth of Independent States Neither

062 Serbia, Republic of Central and Eastern Europe and the Commonwealth of Independent States Neither

063 Montenegro, Republic

of

Central and Eastern Europe and the Commonwealth of Independent States Neither

064 Kosovo, Republic of Central and Eastern Europe and the Commonwealth of Independent States Neither

070 Macedonia Central and Eastern Europe and the Commonwealth of Independent States Neither

081 Albania Central and Eastern Europe and the Commonwealth of Independent States Neither

082 Andorra Industrialized Neither

083 Bulgaria Central and Eastern Europe and the Commonwealth of Independent States Neither

084 Gibraltar Industrialized Neither

085 Iceland Industrialized Neither

086 Liechtenstein Industrialized Neither

087 Monaco Industrialized French

088 Romania Central and Eastern Europe and the Commonwealth of Independent States Neither

089 San Marino Industrialized Neither

090 Holy See Industrialized Neither

099 Western NES Industrialized English

101 Egypt Middle East and North Africa Neither

111 Malawi Eastern and Southern Africa Neither

112 Zambia Eastern and Southern Africa Neither

113 Zimbabwe Eastern and Southern Africa Neither

121 South Africa, Republic

of

Eastern and Southern Africa Neither

122 Namibia Eastern and Southern Africa Neither

130 Tanzania, United

Republic of

Eastern and Southern Africa Neither

131 Algeria Middle East and North Africa French

132 Kenya Eastern and Southern Africa Neither

133 Morocco Middle East and North Africa French

135 Tunisia Middle East and North Africa French

136 Uganda Eastern and Southern Africa Neither

151 Angola Eastern and Southern Africa Neither

152 Lesotho Eastern and Southern Africa Neither

153 Botswana, Republic of Eastern and Southern Africa Neither

154 Burundi Eastern and Southern Africa French

155 Cameroon, Federal

Republic of

West and Central Africa French

156 Chad, Republic of Eastern and Southern Africa French

157 Central Africa Republic Eastern and Southern Africa Neither

158 Congo, Democratic

Republic of

Eastern and Southern Africa French

159 Congo, People's

Republic of the

Eastern and Southern Africa French

160 Benin, Peoples Republic

of

West and Central Africa French

161 Ethiopia Eastern and Southern Africa Neither

162 Eritrea Eastern and Southern Africa Neither

163 Gabon Republic West and Central Africa French

164 Gambia West and Central Africa Neither

165 Ghana West and Central Africa Neither

166 Guinea, Republic of West and Central Africa French

167 Guinea-Bissau West and Central Africa Neither

169 Ivory Coast, Republic of West and Central Africa French

170 Liberia West and Central Africa Neither

171 Libya Middle East and North Africa Neither

172 Madagascar Eastern and Southern Africa French

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73

173 Mali, Republic of West and Central Africa French

174 Mauritania West and Central Africa Neither

175 Mozambique Eastern and Southern Africa Neither

176 Niger, Republic of the West and Central Africa French

177 Nigeria West and Central Africa Neither

178 Guinea, Equatorial West and Central Africa French

179 Rwanda Eastern and Southern Africa French

180 Senegal West and Central Africa French

181 Sierra Leone West and Central Africa Neither

182 Somalia, Democratic

Republic of

Eastern and Southern Africa Neither

183 Djibouti, Republic of Eastern and Southern Africa French

184 Western Sahara West and Central Africa Neither

185 Sudan, Democratic

Republic of

Middle East and North Africa Neither

186 Swaziland Eastern and Southern Africa Neither

187 Togo, Republic of West and Central Africa Neither

188 Burkino-Faso West and Central Africa Neither

198 Macau Sar East Asia Neither

199 Africa NES Eastern and Southern Africa Neither

200 Hong Kong SAR Industrialized Neither

201 Sri Lanka South Asia Neither

202 China, People's Republic

of

East Asia Neither

203 Taiwan East Asia Neither

204 Hong Kong East Asia Neither

205 India South Asia Neither

206 Israel Industrialized Neither

207 Japan Industrialized Neither

208 Lebanon Middle East and North Africa Neither

209 Pakistan South Asia Neither

210 Syria Middle East and North Africa Neither

212 Bangladesh South Asia Neither

213 Palestinian Authority

(Gaza/West Bank)

Middle East and North Africa Neither

221 Cyprus Middle East and North Africa Neither

222 Indonesia, Republic of East Asia Neither

223 Iran Middle East and North Africa Neither

224 Iraq Middle East and North Africa Neither

225 Jordan Middle East and North Africa Neither

226 Kuwait Middle East and North Africa Neither

227 Philippines East Asia Neither

231 Saudi Arabia Middle East and North Africa Neither

241 Myanmar (Burma) East Asia Neither

242 Malaysia East Asia Neither

246 Singapore East Asia English

252 Afghanistan South Asia Neither

253 Bahrain Middle East and North Africa Neither

254 Bhutan South Asia Neither

255 Brunei East Asia Neither

256 Cambodia East Asia Neither

257 Korea, People's

Democratic Republic of

East Asia Neither

258 Korea, Republic of East Asia Neither

260 Laos East Asia Neither

261 Macao East Asia Neither

262 Mongolia, People's

Republic of

East Asia Neither

263 Oman Middle East and North Africa Neither

264 Nepal South Asia Neither

265 Qatar Middle East and North Africa Neither

266 Sikkim (Asia) South Asia Neither

267 Thailand East Asia Neither

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74

268 Tibet East Asia Neither

270 Vietnam, Socialist

Republic of

East Asia Neither

271 North Vietnam East Asia Neither

273 Yemen, Republic of Middle East and North Africa Neither

274 Yemen, People's

Democratic Republic of

Middle East and North Africa Neither

280 United Arab Emirates Middle East and North Africa Neither

299 Asia NES East Asia Neither

305 Australia Industrialized English

339 New Zealand Industrialized English

341 Nauru East Asia English

342 Papau New Guinea East Asia Neither

343 Papau East Asia Neither

399 Australia NES Industrialized English

461 United States of

America

Industrialized English

501 Mexico Latin American and Caribbean Neither

511 Canada Canada English

512 Newfoundland Canada English

521 Greenland Industrialized Neither

531 St. Pierre and Miquelon Industrialized French

541 Belize Latin American and Caribbean English

542 Costa Rica Latin American and Caribbean Neither

543 El Salvador Latin American and Caribbean Neither

544 Guatemala Latin American and Caribbean Neither

545 Honduras Latin American and Caribbean Neither

546 Nicaragua Latin American and Caribbean Neither

547 Panama, Republic of Latin American and Caribbean Neither

548 Panama Canal Zone Latin American and Caribbean Neither

549 Central America NES Latin American and Caribbean Neither

601 Bermuda Industrialized English

602 Jamaica Latin American and Caribbean English

605 Trinidad & Tobago,

Republic of

Latin American and Caribbean English

610 Barbados Latin American and Caribbean English

620 Anguilla Latin American and Caribbean English

621 Antigua and Barbuda Latin American and Caribbean English

622 Bahama Islands, The Latin American and Caribbean English

624 Cayman Islands Latin American and Caribbean English

625 Dominica Latin American and Caribbean Neither

626 Grenada Latin American and Caribbean English

627 Montserrat Latin American and Caribbean English

628 Nevis Latin American and Caribbean Neither

629 St. Kitts-Nevis Latin American and Caribbean English

630 St. Lucia Latin American and Caribbean Neither

631 St. Vincent and the

Grenadines

Latin American and Caribbean English

632 Turks and Caicos Islands Latin American and Caribbean English

633 Virgin Islands, British Latin American and Caribbean English

650 Cuba Latin American and Caribbean Neither

651 Dominican Republic Latin American and Caribbean Neither

652 Netherlands Antilles,

The

Latin American and Caribbean Neither

653 Guadeloupe Latin American and Caribbean French

654 Haiti Latin American and Caribbean French

655 Martinique Latin American and Caribbean French

656 Puerto Rico Latin American and Caribbean Neither

657 Virgin Islands, U.S. Latin American and Caribbean English

658 Aruba Latin American and Caribbean Neither

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75

699 West Indies NES Latin American and Caribbean Neither

703 Argentina Latin American and Caribbean Neither

709 Brazil Latin American and Caribbean Neither

711 Guyana Latin American and Caribbean English

721 Chile Latin American and Caribbean Neither

722 Colombia Latin American and Caribbean Neither

723 Peru Latin American and Caribbean Neither

724 Uruguay Latin American and Caribbean Neither

725 Venezuela Latin American and Caribbean Neither

751 Bolivia Latin American and Caribbean Neither

752 Surinam Latin American and Caribbean Neither

753 Ecuador Latin American and Caribbean Neither

754 French Guiana Latin American and Caribbean French

755 Paraguay Latin American and Caribbean Neither

799 South America NES Latin American and Caribbean Neither

801 Fiji East Asia Neither

821 Southern Antarctic

Territories

Industrialized Neither

822 New Caledonia East Asia French

823 Vanuatu East Asia Neither

824 Solomons, The East Asia Neither

825 Soloman Islands East Asia Neither

826 Tuvalu East Asia Neither

830 Commonwealth of the

Northern Mariana Isl

East Asia Neither

831 Kiribati East Asia Neither

832 Guam East Asia English

833 Marinas East Asia Neither

834 Republic of The

Marshall Islands

East Asia Neither

835 Federated States of

Micronesia

East Asia Neither

836 Republic of Palau East Asia Neither

840 Cook Islands East Asia Neither

841 Wallis And Futuna East Asia Neither

842 Pitcairn Island Industrialized English

843 Samoa, American East Asia Neither

844 Samoa, Western East Asia Neither

845 French Polynesia East Asia French

846 Tonga East Asia Neither

899 Ocean NES East Asia Neither

901 Maldives, Republic of South Asia Neither

902 Mauritius West and Central Africa French

903 Reunion West and Central Africa French

904 Seychelles West and Central Africa French

905 Comoros West and Central Africa Neither

906 Mayotte West and Central Africa Neither

911 Cape Verde Islands West and Central Africa Neither

912 Falkland Islands Industrialized English

914 Sao Tome E Principe West and Central Africa Neither

915 St. Helena Industrialized English

916 East Timor, Democratic

Republic of

East Asia Neither

979 Stateless Other Neither

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Appendix C

Figure IC. Flow chart of patient exclusions for ED visits

6 828 208 ED visits in Ontario for all children from birth to 17

years old who visited an ED from Apr 1, 2003 to Mar 1, 2010

Study population analyzed:

3 322 901 visits (1 555 314 unique children)

Exclusions:

Visits in urgent care centre or mental health facility 390 805

Patient does not live in a CMA of Ontario 2 641 761

ED visits where a patient has had a visit within the previous 30

days 472 741

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77

Figure IIC. Flow chart of patient exclusions for ED revisits

295 457 ED revisits in Ontario for all children from birth to 17 years old

living in a CMA who revisited an ED from Apr 1, 2003 to Mar 8, 2010

288 940 revisits

Exclusions:

Visits in urgent care centre or mental health facility 6 517

Study population analyzed:

249 648 unique revisits

Exclusions:

More than one revisit by the same patient within 7 days of the

index visits 39292