EPB PHC 6000 EPIDEMIOLOGY FALL, 1997 by 80FDZN

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									    EPI 2110, Fall 2004
Principles of Epidemiology


          Instructor:
          Kevin E. Kip, Ph.D.
Assistant Professor, Epidemiology and
 Medicine, Graduate School of Public
Health, Epidemiology Crabtree Hall,
          kipk@edc.pitt.edu
          COURSE OBJECTIVES
Upon completion of this course, the student will:

1. Understand the history and role of
   epidemiology as the basic science for Public
   Health.
2. Develop a population-based perspective of
   disease and other health-related events.
3. Recognize ethical and professional issues in
   the conduct of epidemiologic research.
4. Calculate and interpret epidemiologic
   measures of disease occurrence.
       COURSE OBJECTIVES (cont.)
5. Calculate and interpret measures of effect used
   to compare the risk of disease between
   populations and subgroups.
6. Understand features, strengths, and limitations
   of descriptive, observational, experimental, and
   genetic epidemiologic studies.
7. Distinguish between association and causation,
   including knowledge of criteria to evaluate
   causal associations.
8. Understand roles of chance, bias, and
   confounding in the evaluation of epidemiologic
   research.
        COURSE OBJECTIVES (cont.)
9. Understand the concept of effect measure
   modification.

10. Understand the dynamics on infectious
   disease transmission and methodology used
   to investigate an epidemic outbreak.

11. Understand the role of screening and public
   health surveillance in applied epidemiology.

12. Recognize the impact of racial, ethnic, and
   cultural variability in epidemiologic research.
          Unit 1:

Introduction to Epidemiology
Unit 1 Learning Objectives:

1. Distinguish between the concepts of
   disease and health.
2. Define and understand the uses of
   epidemiology.
3. Distinguish between public health,
   epidemiology, and clinical medicine.
4. Recognize major historical contributions in
   epidemiology.
5. Understand the inter-disciplinary nature of
   epidemiology.
Unit 1 Learning Objectives (cont.):
6. Understand the “epidemiologic transition” of
   causes of mortality from developing to
   developed countries.
7. Understand practical, ethical, and professional
   issues in conducting epidemiologic research.
8. Recognize the role of Institutional Review
   Boards in overseeing the conduct of
   epidemiologic research.
9. Understand the natural history of disease
   progression.
10.Distinguish between primary, secondary, and
   tertiary levels of disease prevention.
         Assigned Readings:

Textbook (Gordis):
  Chapter 1 -- Introduction
  Chapter 20 – Ethical and Professional
    Issues in Epidemiology
  Chapter 5, pages 95-96 (Natural
  history of disease

World Health Report 2003, Chapter 1:
 Global health, today’s challenges,
 pages 1-22.
       DEFINITIONS OF DISEASE

• MULTIPLE DEFINITIONS (E.G.):

• An abnormal condition of an
  organism or part, especially as a
  consequence of infection, inherent
  weakness or environment stress, that
  impairs physiological functioning.
  (1973)
          DEFINITIONS OF DISEASE


• Literally, DIS-EASE, the opposite of ease,
  when something is wrong with a bodily
  function.

• The words “disease”, “illness” and
  “sickness” are loosely interchangeable,
  but are better regarded as not wholly
  synonymous.
        DEFINITIONS OF DISEASE

• Thus, M.W. Susser has suggested that
  they be used as follows:
- Disease is a physiological/psychological
  dysfunction.
- Illness is a subjective state of the person
  who feels aware of not being well.
- Sickness is a state of social dysfunction,
  i.e., a role that the individual assumes
  when ill. (1995)
    PRACTICAL DEFINITION OF
     DISEASE AND EXPOSURE
Disease: broad array of health conditions
  that we seek to understand and ultimately
  modify, including physiologic states,
  mental health, and the entire spectrum of
  human diseases (synonym: outcome
  variable).

Exposure: a catch-all term for agents,
  interventions, conditions, policies, and
  anything that might affect health
  (synonym: predictor/explanatory variable).
  DEFINITIONS OF HEALTH

• WHO: A state of complete physical,
 mental, and social well-being and not
 merely the absence of disease or
 infirmity. (1948)
DEFINITIONS OF HEALTH (cont’d)
• The word “health” is derived from
  the old English “HAL” meaning hale,
  whole, sound in wind and limb.

• The state of an organism functioning
  normally without disease or
  abnormality. (1973)
     Discussion Question 1




When we think of studying “disease”,
  is “disease” a stable concept?
        Discussion Question 1

Probably not, because:
1. Cultural values can influence definitions
  and perceptions of disease (especially
  psychiatric disorders).
2. Improvements in diagnostic
  instrumentation can lead to earlier
  detection of asymptomatic disease.
3. Clinical thresholds for disease
  classification change over time.
     EPIDEMIOLOGY
Greek:   EPI - Upon
         DEMOS - People
         LOGOS - Study of, Body of
                 Knowledge
DEFINITIONS OF EPIDEMIOLOGY


• The study of the distribution and
  determinants of disease frequency in
  human populations. (1970)

• The study of the distribution and
  determinants of health-related states
  or events in specified populations,
  and the application of this study to
  control of health problems. (1988)
DEFINITIONS OF EPIDEMIOLOGY

 The underlying premise of
  epidemiology is that disease not
  occur at random, but rather in
  patterns that reflect the
  operation of underlying factors.
  DEFINITIONS OF PUBLIC HEALTH

• The science and art of :
  1) preventing disease
  2) prolonging life and
  3) promoting health and efficiency
     through organized community effort.
     (1920)
DEFINITIONS OF PUBLIC HEALTH (cont’d)

• To fulfill society’s interest in assuring
  conditions in which people can be healthy.

• The field of health science concerned with
  safeguarding and improving the physical,
  mental and social well-being of the
  community as a whole. (1992)
THE CONTENT OF PUBLIC HEALTH PRACTICE

 • Focus on primary prevention.
 • Community protection through monitoring
   and surveillance for infectious and toxic
   agents.
 • Response to unanticipated natural and
   human-generated disasters.
 • Health promotion through programs to
   notify and educate the community about
   risks and protective measures.
 • Target hard-to-reach populations with
   clinical services.
Why is epidemiology the basic science of
public health?
 PUBLIC HEALTH WORKS BY:
 • Defining a health problem
 • Identifying risk factors associated with the
   problem
 • Developing and testing community-level
   interventions to control or prevent the
   causes of the problem
 • Implementing interventions to improve the
   health of the population; and
 • Monitoring those interventions to assess
   their effectiveness
  EPIDEMIOLOGY HAS THE
  METHODOLOGY TO:

• Determine the extent of disease in the
  community
• Study the natural history and prognosis of
  disease
• Identify associations and potential etiology
  (causes) of a disease and risk factors for
  disease
• Evaluate new preventive and therapeutic
  measures and new modes of health care
  delivery
 EPIDEMIOLOGY HAS THE
 METHODOLOGY TO:

• Provide a foundation for developing
  public policy and regulatory decisions
  relating to environmental problems.

• In short, the primary goal of
  epidemiology is to measure relationships
  between “exposures” and health
  outcomes – these may provide a basis
  for public health initiatives and policies.
     THE RELATIONSHIP BETWEEN
  EPIDEMIOLOGY + CLINICAL PRACTICE
 Clinical Practice Uses Population Data:
• Diagnoses are defined and determined from
  large groups of patients.
• Prognosis is based on experience of large
  groups of patients with the same disease,
  stage of disease, and treatments.
• Selection of therapy is based on the results
  of large treatment studies, such as clinical
  trials.
    Discussion Question 2



Why do we study the epidemiology
 of diseases in large populations,
such as the community, rather than
 focusing on treatment settings?
      Discussion Question 2
Because:
1. Early development of disease can be
   assessed
   more readily in the community.

2. Many individuals with disease do not
   seek treatment.

3. Many individuals with disease do not
   have access to or the resources to
   receive treatment.
     Discussion Question 2
Because:

4. The co-occurrence of multiple diseases,
   and ascertainment of familial risks, is
   better accomplished through an
   epidemiological framework.

5. Threshold levels between sub-clinical
   and clinical disease are better
   determined from individuals not in
   treatment settings.

								
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