Epidemiology: A Basic Science of Public Health

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Epidemiology A Basic Science of Public Health

• Introduction to Epidemiology
• Sharon Cooper, Ph.D.
• May 22, 2001

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• Definitions
• Derivation (Greek)
• Epi (upon)
• Demos (people)
• Logos (doctrine or study)

Short The study of disease occurrence in human
populations.
Long The study of the distribution(1) and
determinants(2) of health-related states or
events in specified populations(3), and the
application of this study to the control(4) of
health problems. Source Last, J.M. (ed.).
Dictionary of Epidemiology, 1988.
(1)distribution disease does not develop at
random certain persons risk due to personal
or environmental factors. Why do some people
develop disease and others do not (describe by
person, place, time)? (2)determinants there
are causes of disease? epidemiologic study
methods?association?procedures for inferring
causation (3)populations clinician vs.
epidemiologist animal vs. human (4)control
goal of epidemiology and public health is
prevention (with or without understanding cause)
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• Epidemiology comprises
• Body of knowledge about occurrence of disease,
  epidemiology of AIDS
• A set of research methods for investigating
  diseases
• Procedures for inferring causes from knowledge of
  patterns of disease

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• II. Scope

• Epidemic (disease gt frequently than expected) vs.
  epidermis (skin)
• Not limited to infectious diseases (?chronic?
• infectious)

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Top 10 Causes of Death in the United States, 1900
and 1990 Rank Cause Deaths/100,000
of Deaths 1900 1 Pneumonia 202
12 2
TB 194 11
3 Diarrhea/enteritis 140 8
4 Heart Disease 137 8 5 Chronic
nephritis 81 5 6 Unint.
Injuries 76 4 7 Stroke 73
4 8 Dis-early infancy 72 4
9 Cancer 64 4 10 Diptheria 40 2 1990
1 Heart disease 290 34
2 Cancer 203 24
3 Stroke 58 7 4 Unint. Injuries 37 4
5 Lung diseases 35 4
6 Pneumonia/flu 32 4 7 Diabetes 19 2
8 Suicide 12 1 9 Liver disease 10 1
10 HIV/AIDS 10 1
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• Applications Epidemiologic used to answer

• Most basic question frequency
• Searches for causes association?infer causation
• Screening (quality of measurement)
• Natural history of disease
• Testing of new treatments or interventions
• Basis to develop public policy

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• Some questions from last few research studiesall
  amenable to epidemiologic investigation

• Is there an increased risk of keratosis (skin
  lesions) among paraquat production workers
  compared to a group of workers not exposed to
  paraquat?
• Is there an increased risk of cancer among
  petrochemical workers in Texas?
• What is the magnitude of work-related injuries in
  adolescents and in which jobs are these injuries
  most likely to occur?
• What was the prevalence of psychiatric conditions
  among women serving in the Persian Gulf War?
  Were adequate health services available to these
  women?

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• Why exciting? ? asking most relevant questions in
  most relevant populations with the goal to
  prevent disease (but, beware of systematic
  errors!)

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I keep six honest serving men (they taught me all
I knew). Their names are what, why, and when And
how and where and who Kipling, 1902
Was Kipling an epidemiologist?!