Transcript Measuring Health and Disease Developed through the APTR Initiative to Enhance Prevention and Population Health Education in collaboration with the Brody School.

Measuring Health and Disease
Developed through the APTR Initiative to Enhance Prevention and Population
Health Education in collaboration with the Brody School of Medicine at East
Carolina University with funding from the Centers for Disease Control and
Prevention
APTR wishes to acknowledge the following individuals that
developed this module:

Kristina Simeonsson, MD, MSPH
Department of Public Health
Brody School of Medicine at East Carolina University

Jeffrey Bethel, PhD
Department of Public Health
Brody School of Medicine at East Carolina University
This education module is made possible through the Centers for Disease Control and Prevention (CDC) and the
Association for Prevention Teaching and Research (APTR) Cooperative Agreement, No. 5U50CD300860. The module
represents the opinions of the author(s) and does not necessarily represent the views of the Centers for Disease
Control and Prevention or the Association for Prevention Teaching and Research.
Define epidemiology and recognize some of its uses
Interpret distribution of disease according to person,
place, and time
 Calculate measures of disease occurrence and
severity
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Study of health and disease among populations
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Basic science of public health
 What causes disease?
 How does disease spread?
 What prevents disease?
 How to control disease?
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Identify etiology and risk factors
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Determine the extent of disease in a population
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Study natural history and prognosis
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Evaluate existing and new preventive and therapeutic
measures/modes of healthcare delivery
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Provide foundation for developing public policy and
regulatory decisions
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The study of the distribution and determinants of
diseases or other health-related outcomes in
populations and the application of this study to
control health problems
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Analysis of disease patterns
 Person
 Place
 Time
Source: National Notifiable Diseases Surveillance System, 2006.
Incidence of acute hepatitis B, by county—United States, 2007
Source: National Notifiable Diseases Surveillance System, 2007.
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Counts
Proportions
 Prevalence
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Rates
 Incidence
 Attack rate
 Mortality rate
 Case fatality rate
 Infant mortality rate
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Measure of disease frequency
Number of cases or other health outcome being
studied
CDC, MMWR Summary of Notifiable Diseases, US 2008
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Answers the question: How common is it?
 Burden of disease in a population
A slice through the population at a point in time at
which it is determined who has the disease and who
does not
 Often stated as a percentage (i.e. per 100)
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# of cases of a disease present in the population
at a specified time
# of persons in the population
at that specified time
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Don’t know when disease developed or the duration
Numerator is a mix of people with different
durations of disease
 Do not have a measure of risk
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Prevalence is appropriate measure of the burden of
a relatively stable chronic condition
 Diabetes
 Hypertension
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Useful for allocating health resources
1990
1999
2009
No Data
<10%
10%–14%
15%–19%
20%–24%
CDC, BRFSS, 1990, 1999, 2009
25%–29%
≥30%
1994
1999
2009
CDC’s Division of Diabetes Translation. National Diabetes
Surveillance System
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Measures change from non-disease to disease
 Can provide a measure of risk
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Also known as incidence rate
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Often stated per 100,000 population per year
# of new cases of a disease
during a specified period of
time
Total number of people at
risk during that period of
time
Department of Health and Human Services, Centers for
Disease Control and Prevention, and National Cancer
Institute, 2010
Department of Health and Human Services, Centers for
Disease Control and Prevention, and National Cancer
Institute, 2010
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Monitor changes over time
Comparisons between groups
 Age-specific rates
 Sex-specific rates
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Goal setting
 Healthy People 2020 Objectives
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Similar to incidence (rate)
Used when nature of the disease is such that
population is observed for a short time period, often
as a result of specific exposure
 Foodborne outbreaks
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Compares the risk of disease in groups with different
exposures
# of people who ate potato salad
who developed gastroenteritis
Total # of people who ate
potato salad
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Prevalence = incidence x duration of disease
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An increased prevalence may reflect
 Increased risk of disease in the population
▪ Increased incidence
 Increased duration of illness
▪ Fewer deaths from the disease (increased survival)
▪ Fewer responses to treatment
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An increased prevalence may reflect
 Increased risk of disease in the population
▪ Increased incidence
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An increased prevalence may also reflect
 Increased duration of illness
▪ Fewer deaths from the disease (increased survival)
▪ Fewer responses to treatment
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Mortality Rate
Case Fatality Rate
Infant Mortality Rate
# of all deaths in one year
# persons in the population at
midyear
# of persons dying during a specified
period after disease onset or
diagnosis
Total # of people with the
specified disease
309 deaths from H5N1
CFR 59%
522 cases of H5N1
WHO website, accessed 2/25/2011
Rabies
Measles
TB
0%
20%
Inapparent
40%
Mild
60%
Moderate
80%
Severe
Mausner & Kramer, 1985
100%
Fatal
National Cancer Institute; A Snapshot of Pancreatic Cancer
# of deaths under one year of age during
a specified time interval
# of live births reported during the
same time period
Expressed per 1,000
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Epidemiology is the basic science of public health
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Count, describe, divide, compare
 Must use rates to compare groups and assess risk
Primary measures of disease occurrence
 Incidence
 Prevalence
 Primary measure of disease severity
 Case fatality rate
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Center for Public Health Continuing Education
University at Albany School of Public Health
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Department of Community & Family Medicine
Duke University School of Medicine
Mike Barry, CAE
Lorrie Basnight, MD
Nancy Bennett, MD, MS
Ruth Gaare Bernheim, JD, MPH
Amber Berrian, MPH
James Cawley, MPH, PA-C
Jack Dillenberg, DDS, MPH
Kristine Gebbie, RN, DrPH
Asim Jani, MD, MPH, FACP
Denise Koo, MD, MPH
Suzanne Lazorick, MD, MPH
Rika Maeshiro, MD, MPH
Dan Mareck, MD
Steve McCurdy, MD, MPH
Susan M. Meyer, PhD
Sallie Rixey, MD, MEd
Nawraz Shawir, MBBS
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Sharon Hull, MD, MPH
President
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Allison L. Lewis
Executive Director
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O. Kent Nordvig, MEd
Project Representative