The Impact of Epidemiology The Impact of Epidemiology in Public Healthin Public Health

Robert Hirokawa, DrPHRobert Hirokawa, DrPHEpidemiologist, Science and Research GroupEpidemiologist, Science and Research Group

HHI / TSP, Hawaii Department of HealthHHI / TSP, Hawaii Department of Health

3 Core Functions of Public Health3 Core Functions of Public Health

The Institutes  of Medicine (IOM) defines the The Institutes  of Medicine (IOM) defines the three core functions of public health as:three core functions of public health as:

AssessmentAssessment

Policy developmentPolicy development

Assurance Assurance

10 Essential Public Health Services10 Essential Public Health Services

Monitor health status to identify community problems.Monitor health status to identify community problems.

Diagnose and investigate health problems and health Diagnose and investigate health problems and health hazards in the community.hazards in the community.

Inform, educate, and empower people about health Inform, educate, and empower people about health issues.issues.

Evaluate effectiveness, accessibility, and quality of Evaluate effectiveness, accessibility, and quality of personal and population- based health services.personal and population- based health services.

Research for new insights and innovative solutions to Research for new insights and innovative solutions to health problems.health problems.

10 Essential Public Health Services10 Essential Public Health Services

Mobilize community partnerships and action to identify and Mobilize community partnerships and action to identify and solve health problems.solve health problems.

Develop policies and plans that support individual and Develop policies and plans that support individual and community health efforts.community health efforts.

Enforce laws and regulations that protect health and ensure Enforce laws and regulations that protect health and ensure safety.safety.

Link people to needed personal health services and assure Link people to needed personal health services and assure the provision of  health care when otherwise unavailable.the provision of  health care when otherwise unavailable.

Assure a competent public health and personal health care Assure a competent public health and personal health care workforce.workforce.

Epidemiology DefinedEpidemiology Defined

The study of The study of distributiondistribution and and determinantsdeterminants of of health and disease in human populationshealth and disease in human populations

3 Essential Components of Epidemiology3 Essential Components of Epidemiology

Disease distribution – person, place, timeDisease distribution – person, place, time

Disease determinants – causal relationshipsDisease determinants – causal relationships

Disease frequencyDisease frequency Expected levelsExpected levels EndemicEndemic EpidemicEpidemic PandemicPandemic

Types of Epidemiologic StudiesTypes of Epidemiologic Studies

DescriptiveDescriptive

AnalyticAnalytic

Descriptive StudiesDescriptive Studies

Frequency of occurrence of a particular Frequency of occurrence of a particular conditioncondition

Patterns of occurrencePatterns of occurrence PersonPerson PlacePlace TimeTime

Hawaii crude adult obesity (BMI Hawaii crude adult obesity (BMI >> 30) prevalence (%) by 30) prevalence (%) by race/ethnicity, BRFSS, 2005race/ethnicity, BRFSS, 2005

0%

10%

20%

30%

40%

50%

% Obese 18.2% 43.1% 13.1% 10.4% 24.4% 19.7%

White Haw aiian Filipino Japanese Others Haw aii

Hawaii crude adult obesity (BMI Hawaii crude adult obesity (BMI >> 30) prevalence (%), 30) prevalence (%), BRFSS, 2005BRFSS, 2005

0%

10%

20%

30%

40%

50%

% obese 19.7% 17.8% 30.9% 24.4%

Haw aii Colorado Mississippi US

Hawaii Obesity and Diabetes TrendsHawaii Obesity and Diabetes Trends

0%

10%

20%

30%

40%

50%

% Obesity 9.1% 10.7% 9.7% 10.3% 10.6% 10.8% 12.9% 13.6% 15.5% 15.7% 15.7% 17.9% 17.1% 16.4% 20.9% 19.7% 20.6%

% Diabetes 3.2% 4.6% 5.0% 5.6% 5.2% 5.2% 6.2% 5.8% 7.6% 6.8% 7.3% 8.2%

1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006

1. Percentage of Hawaii adults that are obese, BRFSS 1990 - 20061. Percentage of Hawaii adults that are obese, BRFSS 1990 - 2006 2. Percentage of Hawaii adults who have been diagnosed with diabetes, BRFSS 1995 - 20062. Percentage of Hawaii adults who have been diagnosed with diabetes, BRFSS 1995 - 2006

Analytic StudiesAnalytic Studies

Observational Studies Observational Studies (exposure not controlled)(exposure not controlled)

Cross-sectionalCross-sectional Case-controlCase-control CohortCohort

Experimental Experimental (exposure controlled)(exposure controlled)

Cross-sectional Study (Observational)Cross-sectional Study (Observational)

Tests the association between variables of interest

Example: obesity and asthmaExample: obesity and asthma

Temporal relationship not taken into account

Case-Control Study (Observational) Case-Control Study (Observational)

Exposure

Disease

Group 1 has disease (Cases)???

Group 2 disease free (Controls)???

Cohort Study (Observational)Cohort Study (Observational)

Exposure

Disease

Group 1 has exposure ???

Group 2 not exposed ???

Basic Presentation of ResultsBasic Presentation of Results

YesYes NoNo TotalsTotals

YesYes 4040 1010 5050

NoNo 6060 9090 150150

TotalsTotals 100100 100100 200200

Smoke?

Lung CA?

Relative Risk = Proportion of disease among those exposed divided by the proportion of disease among those not exposed

Basic Presentation of ResultsBasic Presentation of Results

YesYes NoNo TotalsTotals

YesYes 4040 1010 5050

NoNo 6060 9090 150150

TotalsTotals 100100 100100 200200

Smoke?

Lung CA?

RR = 40/100 divided by 10/100 = .4/.1 = 4

Measurement ErrorsMeasurement Errors

BiasBias RecallRecall MisclassificationMisclassification

ConfoundingConfounding

Statistical ErrorsStatistical Errors

Cause – Effect RelationshipCause – Effect Relationship

Strength of associationStrength of association

ConsistencyConsistency

TemporalityTemporality

Biological plausibilityBiological plausibility

Gradient (dose – response)Gradient (dose – response)

Measures of Disease FrequencyMeasures of Disease Frequency

Prevalence = # of existing cases / total Prevalence = # of existing cases / total populationpopulation

Incidence = # of new cases / total Incidence = # of new cases / total population at riskpopulation at risk

Commonly Used Measures Commonly Used Measures

CrudeCrude

Category-specific (age, gender, geography)Category-specific (age, gender, geography)

Age-adjustedAge-adjusted

Experimental StudyExperimental Study

Clinical TrialClinical Trial Exposure is controlledExposure is controlled

In Summary: In Summary: Impact of Epidemiology in Public HealthImpact of Epidemiology in Public Health

Improved understanding of the distribution and Improved understanding of the distribution and determinants of health and disease in human determinants of health and disease in human populationspopulations

Used to drive program planning, resource Used to drive program planning, resource allocation, interventions, and evaluationallocation, interventions, and evaluation

Thank you!Thank you!