the contribution of population studies to understanding slcn: the whole is greater than the sum of...

The contribution of population studies to understanding SLCN:

The whole is greater than the sum of its partsSheena Reilly

11th May 2015 – Born Talking Seminar - Norwich

Outline • Setting the scene about population studies

• Population vs clinical studies: it’s not a competition • What is the value of population studies?

• What have we learned?• Trajectories • Predictors • Associations • The SLI story

• Data from series of longitudinal, population studies

• Why are we frustrated by some of the findings?

Bridget Taylor – Seminar 1 Jan 2015

• Birth cohorts • Community cohorts• Clinical cohorts or case series

A population view of language

Population: 5.8 million; 1.2 million children

A population view of language

• 6 metropolitan local government areas (LGAs)

• ABS - Socioeconomic Indexes for Areas used to select LGAs• Maroondah & Whitehorse (high SES)• Banyule & Brimbank (middle SES)• Whittlesea & Casey (low SES)

Early language in Victoria Study ELVS

Community – Language focused studies

Longitudinal Clinical or Case series

• Manchester Language Study – Conti-Ramsden• The largest UK study of individuals with a history of SLI.

• A random sample of all 7 year old children who were attending language units in England in 1995.

• Late Talkers Cohort – Rescorla • 53 mother–child dyads from middle class or upper middle class white families.

Population view of low languagePopulations Clinic

presenters

50 85 100 150Non-verbal IQ

Help sought No help sought

4 years of age

7 years of age

Receptive and expressive language & non-verbal performance at 4 and 7 years of age. Help seeking behaviour shown in the 12 months prior

Receptive and expressive language at 4 and 7 years of age: help seeking behaviour in the 12 months prior

Receptive Expressive

Summary of similarities/differences Population/community Clinical

All children or representative sample of children with condition

Sub-group of children with condition

May be referred or self selected because of particular traits e.g. higher parent concern

Full range of ability(s) Likely to be more severe or have co-morbidities

Prospective information available Retrospective re early development

Typically Longitudinal Cross sectional or Longitudinal

Inbuilt comparison group Control group* (recruited if available)

Can extrapolate findings to population Findings only relevant to clinical cohort

*information about early development of control group often retrospective

Bridget Taylor – Seminar 1 Jan 2015

Understanding SLCN• Focus on complex interactions within and between environmental and biological systems• Holistic, not reductionist• Ability to concurrently study speech, language and fluency

Acknowledgments: Jeff Craig

expressive

receptive!

pragmatics grammar

Access to populations has permitted study of language and its inter-connectedness to:

• Other aspects of communication

• Literacy

• Education

• Psychosocial development

• Samples that will be large enough to permit analysis of gene-environment interactions

Population health gains

• What have we learned?• Trajectories • Associations • The SLI story

Knowledge From Our Longitudinal Studies• Typical and disrupted phenotypes (trajectories) of language development• Environmental and biological factors predicting variation

• Social, psychological and educational development

• Health care, education, welfare and societal costs

• Potential for intervention and factors influencing efficacy

Data collection points

8mth 1 2 3 4 5 6 7 8 9 10 11 12 13 14

Q Q Q Q Q Q Q Q Q Q Q T T T T A A A A A A A

Q : parent-report questionnaireA : face-to-face assessment (child and/or adult)T: Teacher reportC: child self report

child & parent

ELVS is measuring• Language & communication

• General development & health

• Family history

• Socio-demographic details

• Mental health & family stress factors

• Parent-child interactions

• Child behaviour & temperament

ELVS Cohort

• N = 1910

• 50.5% male, 49.5% female

• 3.1% (60) premature (<36 weeks)

• 2.8% (53) non-singletons

• 6% (127) speak a language other than English in the home (~ 50 different languages spoken)

287.7234.7

Language: Expressive vocabulary at 2 years

(Reilly et al Pediatrics 2007; Reilly et al IJSLP 2009)

* MB-CDI: Fenson et al, 1994

261.3 words

n =1742

Mean SD Range

Total 261.3 162 0 - 679

Girls 287.7 159.7 0 - 679

Boys 234.7 160.6 0 - 679

< 79 < 119

(Reilly et al Pediatrics 2007; Reilly et al IJSLP 2009)

* MB-CDI: Fenson et al, 1994

Late talkers* at 2 years

19.7% (n = 333)

Average Words

Average words

5%Impaired

2 years 4 years

typical talkers

late talkers

impaired

75%typical

typical14%

14%Impaired

4 years 7 years

typical talkers

impaired

impaired 6%

73.4%typical

typical

4%Impaired

2 years 7 years

typical talkers

late talkers

impaired

75%typical

typical15%

Typical - development in the typical range at each age

Precocious (late) - typical development in infancy followed by high probabilities of precocity from 24 mths onwards

Impaired (early) – delayed development in infancy followed by typical language development thereafter

Impaired (late) -Typical development in infancy but delayed from 24 mths onwards

Precocious (early) - high probabilities of precocity in early life followed by typical language by 48 mths

Ukoumunne et al 2011

Five substantive classes

Characteristics indicative of social advantage were more commonly found in the classes with improving profiles.

Okoumunne et al 2012Characteristics indicative of social advantage were more commonly found in the classes with improving profiles.

And between 4 and 7 years6

4 5 6 7

Child's age in years

High (32.7%) Medium (53.1%) Low (14.2%)

Receptive Language

4 5 6 7

Child's age in years

High (27.1%) Medium (57.9%) Low (15.0%)

Expressive Language

Mean score and 95% confidence interval presented, groups derived by Latent Class Analysis

CELF core age 4 (z score) Change from 4-7 (z score)

Mean diff

95% CI p Mean diff

95% CI p

Disadvantage (1 sd) -0.04 (-0.13, 0.04) 0.31 -0.03 (-0.13, 0.07) 0.61

Family language ability (1 sd)

0.19 (0.13, 0.25) 0.00 0.11 (0.04, 0.18) 0.00

Maternal Education

16-18 vs. post school -0.06 (-0.25, 0.12) 0.51 -0.16 (-0.38, 0.05) 0.13

Less than 16 0.14 (-0.05, 0.34) 0.14 -0.07 (-0.30, 0.16) 0.54

Young Mum2 -0.24 (-0.46, -0.01) 0.04 0.10 (-0.17, 0.37) 0.46

Non English Speaking Background

-0.84 (-1.09, -0.58) 0.00 0.61 (0.31, 0.91) 0.00

1adjusted for child’s gender, IQ, autism, developmental delay, and birth order2up to age 24 at child’s birth

Language at 4 and change from 4 to 7

Individual language & literacy trajectories for 20 children selected at random

Taylor et al 2014

332 low

Language and literacy patterns

4 years

6 years

8 years

318 start low 2474 start middle-high

2,792 CHILDREN

308 low 2484

10 years 381 finish low 2411 finish middle-high

5 most common language and literacy patternsfrom 16 possible patterns for 2792 children

Age 4Languag

Age 6Languag

Age 8Languag

Age 10Literacy

Middle-High Middle-High Middle-High Middle-High

1915 69

Middle-High Middle-High Middle-High Low 202 7

Low Middle-High Middle-High Middle-High 118 4

Low Low Low Middle-High 27 1

Low Low Low Low 26 1

• Start on-track and stay on-track is the most common pattern

• Start behind and stay behind is the least common pattern

• Language & Learning Group, Division of Mental Health, Norwegian Institute of Public Health• Synnve Schjolberg, Group Leader

• Imac Zambrana

• Eivind Ystrom

• Norwegian Research Council

• Norwegian Ministry for Education

• Dept Psychology, University of Oslo• Francisco Pons

Acknowledgements

Trajectories of Language Delay from age 3 to 5Language Delay at 5 years

Language Delay at 3 years

Yes No Total

Yes 318 (3%) 529 (5%) 847 (8%)

No 688 (6.5%) 9 052 (85.5%) 9 740 (92%)

Total 1 006 (9.5%) 9 581 (90.5%) 10 587 (100%)

Yes No Total

Yes 318 (3%) 529 (5%) 847 (8%)

No 688 (6.5%) 9 052 (85.5%) 9 740 (92%)

Total 1 006 (9.5%) 9 581 (90.5%) 10 587 (100%)

Persistent; Transient; Late-Onset

What about the recovered the late talkers?

Dale et al (2014) Am J Speech-Language Pathology 2014

Resolved late talkers: No more at risk of later language imp.than age and gender matched controls

Longitudinal study of twins from age 2 years

Tracked language development at 4, 7 and 12 years

Recommend:Periodic monitoring of recovered late talkers &Screening child in low normal range at school

entry for signs of late language difficulties

Predictors

Predicting Outcomes at 2 & 4 years

2 years:

12 putative risk factors/predictors did NOT strongly predict outcomes

Variation explained (4.3% & 7.0%) by any 1 risk factor was small.

4 years:

Variance explained at 4 years was around 20%Addition of late talking status (2 years) helped explain 23.6% (rec) and 30.4% (exp) language status.

Reilly et al Pediatrics 2007 & 2010

Persistent Language Difficulties at 5 years3% (n=318) of overall sample had persistent language difficulties

38% of children with language delay at 3 years had language difficulties at both time points

Odds of having a persistent language problem:

• Doubled - for boys

• Doubled - family history of late talking

• Doubled - poor comprehension skills at 18mths

• Increased – lower paternal educationEadie et al 2014

Transient Language Difficulties at 5 years5% (n=529) of overall sample had transient

language difficulties between 3 and 5 years

Odds of having a transient problem:

• Increased - family history of • late talking or • speech difficulties

• Increased - poor comprehension skills at 18mths

• Doubled – lower levels of maternal education

• Increased – higher birth order

Eadie et al 2014

Across international studies4, 5, & 8 year old findings corroborate that

More than half of the late talkers do not present with language difficulties at school entry

Trajectories that broadly represent persistent, transient and late onset language impairment exist across languages

Poor early comprehension skills are a strong & consistent predictor of persistent problems, particularly for girls

Family history of speech, language & literacy difficulties is important & may be a discriminating factor regarding language trajectories

Eadie et al 2014

Associations

The association between child language problems and social, emotional & behavioural difficulties from 4-7 yearsA population-based longitudinal study

Associations

In a population-based sample of 4-7 year old children

To examine cross-sectional relationship between Low Language and SEB Difficulties @ ages 4, 5 and 7

To describe the pathways of LL and SEB Difficulties over time

Measures of key constructs

Construct

4yo 5yo 7yo

Language CELF-P2*

CELF-4^

CELF-4

SEB Difficulties

SDQ# SDQ SDQ

*Clinical Evaluation of Language Fundamentals – Preschool Edition (2nd)^ Clinical Evaluation of Language Fundamentals – 4th Edition – Australian Edition# Strengths and Difficulties Questionnaire

Strengths & Difficulties QuestionnaireSDQ Domain

Hyperactivity/inattentionConduct problemsPeer problemsEmotional problemsProsocial behaviour

Total Difficulties

• 25 items • Parent report• 3-point scale - not true, somewhat true,

certainly true

Movement between groups over time

Typical Language & Typical SEB

Only Low Language

Only SEB Difficulty

Low Language & SEB Difficulty

610 (79%)

76 (10%)

59 (8%)

26 (3%)

4 years of age n (%)

5 years of age %

7 years of age %

Only Low Language

Only SEB Difficulty

610 (79)

26 (3)

4 years of age %

5 years of age %

7 years of age %

No Low Language & No SEBD

Low Language only

SEBD only

Low Language & SEBD

4 years of age %

5 years of age %

7 years of age %

Only Low Language

Only SEB Difficulty

568 (93)

12 (2)

38 (64)

19 (32)1 (2)

5 (19)

8 (31)5 (19)

8 (31)

29 (5)

34 (45)

34 (45)2 (3)

4 years of age %

5 years of age %

7 years of age %

568 (93)

12 (2)

38 (64)

19 (32)1 (2)

5 (19)

8 (31)5 (19)

8 (31)

29 (5)

34 (45)

34 (45)2 (3)

50 (8)

28 (4)

21 (29)

3 (4)6 (8)

19 (50)

12 (32)

4 (11)

2 (13)

5 (31)3 (19)

6 (38)

42 (58)

561 (87)

Only Low Language

Only SEB Difficulty

Summary

• Strong relationship between LL & SEB problems in children aged 4, 5 & 7 years of age

• LL children experience more SEB difficulties

• Great fluidity & complexity in both language and SEB development over time

The SLI story

56Reilly et al 2014

Introduction of the term ‘specific’ and SLI

Descriptions of clinical cases or series of cases

Case control studies

Epidemiology

Medicine, Paediatrics, Speech Pathology, Linguistics, Developmental Psychology

Observation has driven theoretical approaches

Reilly et al 2014

Typical LanguageSLI

Non-Specific LI

Tomblin and Nippold 2014

Low Language versus SLI (expressive)50

anguage

50 86 100 150non-verbal IQ

Specific Language Impairment Typical development

Developmental Delay typical language - low non-verbal score

Expressive language versus non-verbal IQ

• Typical language + Low NV• Low Language + Low NV

• Typical language + Typical NV• Low Language + Typical NV

20.6% with Low Language

Receptive and Expressive Language standard scores and non-verbal performance 4 years 7 years

^ Language & NV IQ within normal range; ☐ Low NV IQ & Language within normal range; X – SLI; - Low Language and NV IQ

• Two cohorts - Two countries

• Different language measures

• Iowa - children with SLI and NSLI continuously distributed across range of scores

• The two categories derived from recognised cutpoints are somewhat arbitrary.

• Children with SLI only differed in language severity scores - significantly higher mean language scores than children with NSL

Marked social gradient for language outcomes:

Three large scale population studies: - Millenium Cohort Study (MCS) British Abilities Scale - Naming Vocabulary at 5 years by Index of Multiple Deprivation quintile

- Growing up in Scotland (GUS) British Abilities Scale – Naming Vocabulary at 5 years by Index of Multiple Deprivation quintile

- Early Language in Victoria Study (ELVS) Clinical Evaluation of Language Fundamentals (CELF-P2) Core Language at Five years by SEIFA Quintiles

Law et al 2013; Reilly et al 2013; Reilly et al 2014

1 2 3 4 5

ELVS 5yo CELF-P2 Core Score by SEIFA quintiles

MCS GUS

Are outcomes different depending on classification

Findings from three longitudinal population studies:

- Dollaghan (2004): 3 -4 year olds- Tomblin et al 2013: 10 and 16 year olds

- Law et al 2009: 34 year olds

Dollaghan (2004)

620 participants drawn from a larger study (n=6000) of otitis media in a socio-demographically diverse population in Pittsburgh, USA.

At 3-4 years Language scores were evenly distributed

- No evidence of an SLI taxon. - Children with SLI were not a qualitatively

distinct group

SLI & NSLI significantly greater levels of behaviour problems than typical controls

SLI & NSLI - similar patterns in psychosocial outcomes at both ages.

Tomblin et al – Iowa study

*Achenbach Child Behavior Checklist (CBCL) Teacher Report Form

16 years: children with poor language - less socially skilled regardless of performance IQ.

Psychosocial outcomes* for 6 year olds (SLI and NSLI) at 10 and 16 years of age

Conclusion: poor language skills at school entry confers elevated risk for psychosocial problems both in the

middle and end of the school years.Risk NOT altered by the child’s performance IQ.

Law et al 2009

Adult literacy difficulties: N-SLI group (OR: 4.35); SLI group (OR 1.59)

Adult mental health difficulties:

Low employment: SLI group (OR 2.24) than for the N-SLI group (OR1.88).

Having SLI and N-SLI at 5 years was associated with:

Long term risk of early language difficulties is importantIn each case significant predictors of adult outcomes were social factors

• Summary

Summary

• Trajectories

Preschool (3 years)

Kindergarten (4 years)

Primary school (5 years)

Set priorities for research into Language ImpairmentDevelopment of practical tools:

Risk prediction tools that will zero in on children destined for lasting Language Impairment

• Not linear • The way language develops is complex and can accelerate,

plateau and sometimes go backwards.• These fluctuating developmental pathways make it hard to

accurately predict persistent Language Impairment

• A strong biological trajectory dominant in the early years; social disadvantage helps explain more variance in outcome by 4 years.

• Gap may widen by 4 years - possibly because of cumulative exposure to less rich language environments

Summary

• Contrasting with fluidity to age 4, language ability across the child population is better delineated from ages 4 to 7

• But there is potential for change in the individual child• Family language environment was the most salient social risk

factor

• Activation and acceleration rates vary

• Surveillance rather than screening approach may be required

• Language development - vulnerable to further disruption by social disadvantage in the later preschool years.

• While sobering, offers a fairly prolonged window of early childhood during which these impacts could be genuinely prevented, rather than simply ameliorated.

Clinical and Public Health implications

Summary

• Predictors

Predictors

• Unlikely to be helpful in screening for language delay in the earlier years (< 2 years)

• More helpful in identifying children with Low Language by 4 years

Recommendation• Language promotion activities in infants younger than 24

months – targeted and based on the level of communication skills displayed

Summary

• Associations

Summary

• Strong relationship between LL & SEB problems in children aged 4, 5 & 7 years of age

• LL children experience more SEB difficulties

• Great fluidity & complexity in both language and SEB development over time

Summary

• SLI

• Remove ‘specific’ and use the term Language Impairment (LI)

• Abandon the exclusionary criteria*

• Whilst they are convenient for experimental research they do not reflect the real world where symptoms and conditions may overlap and co-morbidity may emerge over time.

• Agree definition and criteria for research and test these in existing population studies to inform clinical services and policy

* All of them?

• Summary

New knowledge

• Access to populations has revealed levels of complexity not recognisable in case-control designs.

• More complex than persistent vs resolution

• Appreciation of continuities and fluctuations with

fluidity -continuing into school years

• IQ discrepancy not relevant to long term language outcomes

• Exclusion criteria create convenient ‘research’ groups • Maybe important for imaging studies

• Social gradient strong – language hyper sensitive to disadvantage

Fitting policies and services to language patterns

• The job of fitting policies and services to language patterns is easier if language patterns are stable and predictable

• The job of fitting policies and services to language patterns is NOT easy when language patterns are unstable and unpredictable

• Based on the patterns we see, we have to ask the question, “How well do policies and services fit these language patterns?

Acknowledgement to Cate Taylor CRE conference 2014

Fitting population patterns to clinical context

• Speech pathologists• The patterns you observe in children in specialist service systems

may not fit the patterns we see in the general population

• Your job is to change growth trajectories

• Unstable growth patterns provide more scope for change than stable growth patterns (e.g., height)

Acknowledgement to Cate Taylor CRE conference 2014It’s called curiosity

Shifting to personalised and population medicine

• “….. clinicians have a responsibility to the population they serve, to the patients they never see, as well as to the patients who have consulted/been referred.

• “….. clinicians, while still focused on the needs of the individual …… when in the consultation, also make decisions about the allocation and use of resources to maximise value for all the people….they serve

• “This is different from management of a service for the patients who present to the service”.

Gray, A. (2013). The art of medicine: The shift to personalised and population medicine. The Lancet, 382, 200-2001.

‘The new responsibilities for the clinician practicing population “speech pathology”* not only includes maximising value by getting the right outcomes for the right patients in the right place with the least use of resources, but also ensuring the prevention of inequity related to age or gender or race or social class’.

‘Population “speech pathology”* is not a new specialty, it is a new paradigm that I believe every clinician will sooner or later adopt, with a proportion of clinicians being allocated explicit time for working for the whole population’.

* Inserted

LANGUAGE DEVELOPMENT & DISORDER:

“There are known knowns. These are things we know that we know. There are known unknowns. That is to say, there are things that we know we don't know. But there are also unknown unknowns. There are things we don't know we don't know.”

Acknowledgements• Centre for Research Excellence in Child Language -

Gold, Goldfeld, Law, McKean, Mensah, Morgan, Tomblin, Wake,

• Early Language In Victoria Study - Bavin, Bretherton, Carlin, Eadie, Gold, Prior, Mensah, Okoumunne, Wake.

• Hearing Language and Literacy group - Cini, Conway, Pezic

• Cate Taylor

Thankyou

Research Snapshots: late talking

www.mcri.edu.au/CREchildlanguage

Morbidities of language delay

SDQ subscale Language impairmenta

M (SD)

No language impairmentb

M (SD)

p value Effect size

Emotional problems

2.0 (2.1) 1.6 (1.7) 0.006 0.2

Conduct problems 1.8 (1.7) 1.3 (1.5) <0.001 0.3

Hyperactivity-inattention

4.1 (2.7) 2.8 (2.3) <0.001 0.5

Peer problems 1.2 (1.7) 0.9 (1.3) 0.005 0.2

Prosocial behaviour

8.1 (1.9) 8.4 (1.6) 0.05 -0.2

Total difficulties 9.0 (4.7) 6.6 (4.7) <0.001 0.5

Social, emotional & behavioural difficulties with language impairment @ 7 yearsa N=189; b N=881

the contribution of population studies to understanding slcn: the whole is greater than the sum of...

value of population

study of language

expressive language

language units

population health gains

series of longitudinal

sli story data

year old children

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