EPI 810: Introduction To EPI 810: Introduction To EpidemiologyEpidemiology

Nigel Paneth Lecture 810 1.1

Syllabus: Time, Place, and Syllabus: Time, Place, and PersonPerson

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

READINGSREADINGS Required Texts:

1) Leon Gordis: Epidemiology. 3rd edition, 2004

2) Articles: In Department of Epidemiology library, labeled as EPI 810 Articles

Highly recommended Texts1) Last J M, A Dictionary of

Epidemiology, 4th edition 2001 2) Chin J: Control of Communicable

Disease Manual, 17th edition (required for EPI 817)

EVALUATIONEVALUATION

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 DATESIMPORTANT 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 DUE DATES FOR COMPONENTS OF PAPERCOMPONENTS OF PAPER

1. TOPIC MON 9/202. 10 ITEM BIBLIOGRAPHY WED 9/29 3. ONE PAGE OUTLINE MON 10/184. FIRST DRAFT WED 11/105. FINAL DRAFT MON 12/6

DRAFT COMMENTSDRAFT 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?What is Epidemiology?

Two Definitions of an EpidemicTwo 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 Definitions of Epidemiology

Oxford English Dictionary THE BRANCH OF MEDICAL SCIENCE WHICH TREATS

OF EPIDEMICS

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

THEIR PREVENTIONAnderson G,quoted in Rothman KJ: Modern

EpidemiologyTHE STUDY OF THE OCCURRENCE OF ILLNESS

Definitions of EpidemiologyDefinitions 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 What Is The Unique Skill Of Epidemiologists?Of Epidemiologists?

MEASURING DISEASE FREQUENCY IN

POPULATIONS

Measuring Disease Frequency Measuring Disease Frequency Has Several ComponentsHas 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

Two Broad Types of Two Broad Types of EpidemiologyEpidemiology

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

DESCRIPTIVE EPIDEMIOLOGY ANALYTIC EPIDEMIOLOGY

The Basic Triad Of The Basic Triad Of

Descriptive EpidemiologyDescriptive Epidemiology THE THREE ESSENTIAL CHARACTERISTICS OF DISEASE WE LOOK FOR IN DESCRIPTIVE EPIDEMIOLOGY:

TIME PLACE PERSON

TimeTime

Changing or stable?

Seasonal variation.

Clustered (epidemic) or evenly distributed (endemic)?

Point source or propagated.

PlacePlace

Geographically restricted or widespread (pandemic)?

 Relation to water or food supply.

 Multiple clusters or one?

PersonPersonAge

Socio-economic status

Gender

Ethnicity/Race

Behavior

Descriptive Epidemiology Is A Descriptive Epidemiology Is A Necessary Antecedent Of Necessary Antecedent Of

Analytic EpidemiologyAnalytic 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 The Basic Triad Of Analytic EpidemiologyAnalytic Epidemiology

THE THREE PHENOMENA ASSESSED IN ANALYTIC EPIDEMIOLOGY ARE:

HOST

ENVIRONMENTAGENT

AgentsAgents

NutrientsPoisons Allergens Radiation Physical trauma Microbes Psychological experiences

Host FactorsHost Factors

Genetic endowment

Immunologic state

Age

Personal behavior

EnvironmentEnvironment

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 EpidemiologyPurposes Of Epidemiology

(Gordis: Epidemiology, p. 3-4)(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 Differences Between Laboratory Sciences And Field Laboratory Sciences And Field

SciencesSciences

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 Differences Between Laboratory Sciences And Field Laboratory Sciences And Field

SciencesSciencesIn 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

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%

EVERY HEALTH OUTCOME HAS SOME INTERESTING AND USEFUL EPIDEMIOLOGIC

CHARACTERISTIC

DEATH RATES BY SOCIAL CLASS FROM A CERTAIN CAUSE AMONG 1,316 PEOPLE

WHAT CAUSE OF DEATH IS THIS?

The previous slide shows death The previous slide shows death rates by class of ticket on the rates by class of ticket on the

Titanic, a large ocean liner that Titanic, a large ocean liner that sank after colliding with an sank after colliding with an

iceberg in 1912 iceberg in 1912