The Impact of Epidemiology in Public Health Robert Hirokawa, DrPH Epidemiologist, Science and Research Group HHI / TSP, Hawaii Department of Health

3 Core Functions of Public Health The Institutes of Medicine (IOM) defines the three core functions of public health as: Assessment Assessment Policy development Policy development Assurance Assurance

10 Essential Public Health Services Monitor health status to identify community problems. Diagnose and investigate health problems and health hazards in the community. Inform, educate, and empower people about health issues. Evaluate effectiveness, accessibility, and quality of personal and population- based health services. Research for new insights and innovative solutions to health problems.

10 Essential Public Health Services Mobilize community partnerships and action to identify and solve health problems. Develop policies and plans that support individual and community health efforts. Enforce laws and regulations that protect health and ensure safety. Link people to needed personal health services and assure the provision of health care when otherwise unavailable. Assure a competent public health and personal health care workforce.

Epidemiology Defined The study of distribution and determinants of health and disease in human populations

3 Essential Components of Epidemiology Disease distribution – person, place, time Disease determinants – causal relationships Disease frequency Expected levels Expected levels Endemic Endemic Epidemic Epidemic Pandemic Pandemic

Types of Epidemiologic Studies DescriptiveAnalytic

Descriptive Studies Frequency of occurrence of a particular condition Patterns of occurrence Person Person Place Place Time Time

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

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

Hawaii Obesity and Diabetes Trends 1. Percentage of Hawaii adults that are obese, BRFSS Percentage of Hawaii adults who have been diagnosed with diabetes, BRFSS Percentage of Hawaii adults who have been diagnosed with diabetes, BRFSS

Analytic Studies Observational Studies (exposure not controlled) Cross-sectional Cross-sectional Case-control Case-control Cohort Cohort Experimental (exposure controlled)

Cross-sectional Study (Observational) Tests the association between variables of interest Example: obesity and asthma Example: obesity and asthma Temporal relationship not taken into account

Case-Control Study (Observational) ExposureDisease Group 1 has disease (Cases)??? Group 2 disease free (Controls)???

Cohort Study (Observational) ExposureDisease Group 1 has exposure??? Group 2 not exposed???

Basic Presentation of Results YesNoTotals Yes No Totals Smoke? Lung CA? Relative Risk = Proportion of disease among those exposed divided by the proportion of disease among those not exposed

Basic Presentation of Results YesNoTotals Yes No Totals Smoke? Lung CA? RR = 40/100 divided by 10/100 =.4/.1 = 4

Measurement Errors Bias Recall Recall Misclassification MisclassificationConfounding Statistical Errors

Cause – Effect Relationship Strength of association ConsistencyTemporality Biological plausibility Gradient (dose – response)

Measures of Disease Frequency Prevalence = # of existing cases / total population Incidence = # of new cases / total population at risk

Commonly Used Measures Crude Category-specific (age, gender, geography) Age-adjusted

Experimental Study Clinical Trial Exposure is controlled Exposure is controlled

In Summary: Impact of Epidemiology in Public Health Improved understanding of the distribution and determinants of health and disease in human populations Used to drive program planning, resource allocation, interventions, and evaluation

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