EPI 810: Introduction To Epidemiology Nigel Paneth Lecture

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 ;

READINGS Required Texts: 1) Leon Gordis: Epidemiology. 3rd edition, ) Articles: In Department of Epidemiology library, labeled as EPI 810 Articles Highly recommended Texts 1) Last J M, A Dictionary of Epidemiology, 4 th edition ) Chin J: Control of Communicable Disease Manual, 17 th 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 EXAMTHUR Dec 16 5:45

DUE DATES FOR COMPONENTS OF PAPER 1. TOPIC MON 9/ ITEM BIBLIOGRAPHYWED 9/29 3. ONE PAGE OUTLINEMON 10/18 4. FIRST DRAFTWED 11/10 5. FINAL DRAFTMON 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 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 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 DESCRIPTIVE EPIDEMIOLOGYANALYTIC EPIDEMIOLOGY

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 ENVIRONMENTAGENT

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

MenWomenChildrenTotal 1 st class67%3%038% 2 nd class92%14%059% 3 rd class84%54%66%62% Total82%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 rates by class of ticket on the Titanic, a large ocean liner that sank after colliding with an iceberg in 1912