EPI 810 Introduction To Epidemiology - PowerPoint

							EPI 810: Introduction To
     Epidemiology


      Nigel Paneth
     Lecture 810 1.1
Syllabus: Time, Place, and
          Person
   Time:     Mondays and Wednesdays
              4:10-5:20 p.m.
   Office hours: BY ARRANGEMENT
   Place: Room A -131 East Fee Hall
           – Department of Epidemiology
              classroom.
   Person: Nigel Paneth, Instructor.
              • 353-8623; paneth@msu.edu
               READINGS
   Required Texts:
      1) Leon Gordis: Epidemiology. 3rd edition,
    2004
      2) Articles: In Department of Epidemiology
            library, labeled as EPI 810 Articles

   Highly recommended Texts
      1) Last J M, A Dictionary of Epidemiology,
            4th edition 2001
      2) Chin J: Control of Communicable
    Disease Manual, 17th edition (required for
    EPI 817)
              EVALUATION

   Two tests (in classroom)
     – Midterm (15% )
     – Final exam (30%)
   Class participation (15%)
   Term paper (40%)
   No assigned exercises but be prepared to go
    over exercises at back of chapters in class
         IMPORTANT DATES
       NO CLASSES ON

    –     MON Sept 6 (Labor day)
    –     WED Nov 24 (Thanksgiving eve)

       INSTRUCTOR AWAY WEEK OF NOVEMBER 1

    –     MON Nov 1 - Mid-term
    –     WED Nov 3 - Special session on searching public
                      health databases

       OPTIONAL REVIEW SESSION      MON Dec 6

       FINAL EXAM                   THUR Dec 16 5:45
   DUE DATES FOR
COMPONENTS OF PAPER

1. TOPIC                  MON   9/20
2.   10 ITEM BIBLIOGRAPHY WED   9/29
3.   ONE PAGE OUTLINE     MON   10/18
4.   FIRST DRAFT          WED   11/10
5.   FINAL DRAFT          MON   12/6
       DRAFT COMMENTS

 MINOR REVISIONS - About a 3.5 in its
  present state, can get up to around 4.0
  with modest effort
 SOME REVISION - About a 3.0 in its
  present state, needs more work to get a
  grade near or at 4.0
 MAJOR/MUCH REVISION – Only at about
  2.5 now – really needs work to get up to
  good grade. Consider meeting with me
What is Epidemiology?
     Two Definitions of an Epidemic
Last JM: A Dictionary of Epidemiology. 4th ed
  THE OCCURRENCE IN A COMMUNITY OR REGION OF CASES
  OF AN ILLNESS, SPECIFIC HEALTH-RELATED BEHAVIOUR, OR
  OTHER HEALTH-RELATED EVENTS CLEARLY IN EXCESS OF
  NORMAL EXPECTANCY.


From the Babylonian Talmud (Tractate Taanit, 21A)

A CITY THAT HAS FIFTEEN HUNDRED MILITARY AGE MEN SUCH
AS AKKO, AND THAT SUFFERS NINE DEATHS IN THREE DAYS,
THAT IS CONSIDERED A PLAGUE. A CITY WITH FIVE HUNDRED
SUCH AS AMIKO, AND HAS THREE DEATHS IN THREE DAYS,
THAT IS CONSIDERED A PLAGUE.
  Definitions of Epidemiology

Oxford English Dictionary
THE BRANCH OF MEDICAL SCIENCE WHICH TREATS
  OF EPIDEMICS

Kuller LH: Am J Epid 1991;134:1051
EPIDEMIOLOGY IS THE STUDY OF "EPIDEMICS"
  AND THEIR PREVENTION

Anderson G,quoted in Rothman KJ: Modern
  Epidemiology
THE STUDY OF THE OCCURRENCE OF ILLNESS
 Definitions of Epidemiology

Lilienfeld A: in Foundations of Epidemiology

   THE STUDY OF THE DISTRIBUTION OF A DISEASE OR
  A PHYSIOLOGICAL CONDITION IN HUMAN
  POPULATIONS AND OF THE FACTORS THAT INFLUENCE
  THIS DISTRIBUTION

  Last JM: A Dictionary of Epidemiology

  THE STUDY OF THE DISTRIBUTION AND
  DETERMINANTS OF HEALTH RELATED STATES AND
  EVENTS IN POPULATIONS AND THE APPLICATION OF
  THIS STUDY TO CONTROL OF HEALTH PROBLEMS“
What Is The Unique Skill
 Of Epidemiologists?

             MEASURING
              DISEASE
            FREQUENCY IN
            POPULATIONS
    Measuring Disease Frequency
      Has Several Components

   Classifying and              Defining the period of
    categorizing disease          time of risk of disease

   Deciding what                Obtaining permission to
    constitutes a case of         study people
    disease in a study
                                Making measurements of
   Finding a source for          disease frequency
    ascertaining the cases
                                 Relating cases to
   Defining the population       population and time at
    at risk of disease            risk
                 Two Broad Types of
                   Epidemiology

DESCRIPTIVE EPIDEMIOLOGY              ANALYTIC EPIDEMIOLOGY
Examining the distribution of a       Testing a specific hypothesis
disease in a population, and          about the relationship of a
observing the basic features of its   disease to a putative cause, by
distribution in terms of time,        conducting an epidemiologic
place, and person.                    study that relates the
                                      exposure of interest to the
Typical study design:                 disease of interest.
community health survey
(approximate synonyms - cross-        Typical study designs: cohort,
sectional study, descriptive          case-control
study)
         The Basic Triad Of
      Descriptive Epidemiology
    THE THREE ESSENTIAL CHARACTERISTICS
    OF DISEASE WE LOOK FOR IN DESCRIPTIVE
    EPIDEMIOLOGY:

 TIME
 PLACE
 PERSON
                 Time

   Changing or stable?

   Seasonal variation.

   Clustered (epidemic) or evenly
    distributed (endemic)?

   Point source or propagated.
                 Place

   Geographically restricted or
    widespread (pandemic)?

   Relation to water or food supply.

   Multiple clusters or one?
               Person
   Age

   Socio-economic status

   Gender

   Ethnicity/Race

   Behavior
  Descriptive Epidemiology Is A
    Necessary Antecedent Of
    Analytic Epidemiology

To undertake an analytic
  epidemiologic study you must first:
 Know where to look
 Know what to control for
 Be able to formulate hypotheses
  compatible with laboratory
  evidence
A COMMON ERROR IN EPIDEMIOLOGY IS
 MOVING TO ANALYTIC EPIDEMIOLOGY
WITHOUT HAVING A SOLID BASE IN THE
 DESCRIPTIVE EPIDEMIOLOGY OF THE
           CONDITION.


  THUS THE FIRST THREE OF
 THE FIVE SECTIONS OF THIS
     COURSE DEAL WITH
 DESCRIPTIVE EPIDEMIOLOGY
     The Basic Triad Of
    Analytic Epidemiology
 THE THREE PHENOMENA ASSESSED IN
ANALYTIC EPIDEMIOLOGY ARE:
             HOST




  AGENT               ENVIRONMENT
             Agents

 Nutrients
 Poisons
 Allergens
 Radiation
 Physical trauma
 Microbes
 Psychological experiences
          Host Factors

   Genetic endowment

   Immunologic state

   Age

   Personal behavior
               Environment

 Crowding
 Atmosphere
 Modes of communication – phenomena
  in the environment that bring host and
  agent together, such as:
    – Vector
    – Vehicle
    – Reservoir
  Epidemiologists are required to have some
  knowledge of the disciplines of public health,
  clinical medicine, pathophysiology, statistics, and
  the social sciences.

• public health, because of the emphasis on disease prevention.
• clinical medicine, because of the emphasis on disease
classification and diagnosis.
• pathophysiology, because of the need to understand basic
biological mechanisms in disease.
• statistics, because of the need to quantify disease frequency
and its relationships to antecedents.
• social sciences, because of the need to understand the social
context in which disease occurs and presents.
        Purposes Of Epidemiology
      (Gordis: Epidemiology, p. 3-4)
1.   Identify causes and risk factors for
     disease.
2.   Determine the extent of disease in the
     community.
3.   Study natural history and prognosis of
     disease.
4.   Evaluate preventive and therapeutic
     measures
5.   Provide foundation for public policy
            Differences Between
        Laboratory Sciences And Field
                  Sciences
In the Laboratory:

• Mostly experimental
• Variables controlled by the investigator
• All variables known
• Replication easy
• Results valid
• Meaning of results for humans uncertain.
• Little need for statistical manipulation of data.
• Highly equipment intensive
           Differences Between
       Laboratory Sciences And Field
                 Sciences
In the Field:

   Mostly observational
   Variables controlled by nature
   Some variables unknown
   Replication difficult; exact replication impossible
   Results often uncertain
   Meaning of results for humans clear
   Statistical control often very important
   Highly labor intensive
   EVERY HEALTH OUTCOME HAS SOME
INTERESTING AND USEFUL EPIDEMIOLOGIC
           CHARACTERISTIC
 DEATH RATES BY SOCIAL CLASS FROM A
 CERTAIN CAUSE AMONG 1,316 PEOPLE

              Men   Women   Children   Total
  1st class   67%    3%        0       38%

  2nd class   92%   14%        0       59%
  3rd class   84%   54%      66%       62%
   Total      82%   26%      48%       62%


       WHAT CAUSE OF DEATH IS THIS?
The previous slide shows death
 rates by class of ticket on the
Titanic, a large ocean liner that
   sank after colliding with an
         iceberg in 1912