EPI 810: Introduction To Epidemiology

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EPI 810 Introduction To Epidemiology

• Nigel Paneth
• Lecture 810 1.1

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Syllabus Time, Place, and Person

• Time Mondays and Wednesdays 410-520
  p.m.
• Office hours BY ARRANGEMENT
• Place Room A -131 East Fee Hall
• Department of Epidemiology classroom.
• Person Nigel Paneth, Instructor.
• 353-8623 paneth_at_msu.edu
  

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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)

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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

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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 16 545

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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

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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

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What is Epidemiology?
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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.
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Definitions of Epidemiology

• Oxford English Dictionary
• THE BRANCH OF MEDICAL SCIENCE WHICH TREATS OF
  EPIDEMICS
• Kuller LH Am J Epid 19911341051
• EPIDEMIOLOGY IS THE STUDY OF "EPIDEMICS" AND
  THEIR PREVENTION
• Anderson G,quoted in Rothman KJ Modern
  Epidemiology
• THE STUDY OF THE OCCURRENCE OF ILLNESS

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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

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What Is The Unique Skill Of Epidemiologists?
MEASURING DISEASE FREQUENCY IN POPULATIONS
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Measuring Disease Frequency Has Several
Components

• Classifying and categorizing disease
• Deciding what constitutes a case of disease in a
  study
• Finding a source for ascertaining the cases
• Defining the population at risk of disease

• Defining the period of time of risk of disease
• Obtaining permission to study people
• Making measurements of disease frequency
• Relating cases to population and time at risk

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Two Broad Types of Epidemiology
DESCRIPTIVE EPIDEMIOLOGY
ANALYTIC EPIDEMIOLOGY

• Examining the distribution of a disease in a
  population, and observing the basic features of
  its distribution in terms of time, place, and
  person.
• Typical study design
• community health survey (approximate synonyms -
  cross-sectional study, descriptive study)

• Testing a specific hypothesis about the
  relationship of a disease to a putative cause, by
  conducting an epidemiologic study that relates
  the exposure of interest to the disease of
  interest.
• Typical study designs cohort,
  case-control

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The Basic Triad Of Descriptive Epidemiology

• THE THREE ESSENTIAL CHARACTERISTICS OF DISEASE
  WE LOOK FOR IN DESCRIPTIVE EPIDEMIOLOGY
• TIME
• PLACE
• PERSON

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Time

• Changing or stable?
• Seasonal variation.
• Clustered (epidemic) or evenly distributed
  (endemic)?
• Point source or propagated.

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Place

• Geographically restricted or widespread
  (pandemic)?  
• Relation to water or food supply.  
• Multiple clusters or one?

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Person

• Age
• Socio-economic status
• Gender
• Ethnicity/Race
• Behavior

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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

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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

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The Basic Triad Of Analytic Epidemiology

• THE THREE PHENOMENA ASSESSED IN ANALYTIC
  EPIDEMIOLOGY ARE

HOST
ENVIRONMENT
AGENT
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Agents

• Nutrients
• Poisons
• Allergens
• Radiation
• Physical trauma
• Microbes
• Psychological experiences

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Host Factors

• Genetic endowment
• Immunologic state
• Age
• Personal behavior

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Environment

• Crowding
• Atmosphere
• Modes of communication phenomena in the
  environment that bring host and agent together,
  such as
• Vector
• Vehicle
• Reservoir

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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.
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Purposes Of Epidemiology(Gordis Epidemiology,
p. 3-4)

• Identify causes and risk factors for disease.
• Determine the extent of disease in the community.
• Study natural history and prognosis of disease.
• Evaluate preventive and therapeutic measures
• Provide foundation for public policy

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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

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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

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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?
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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