Introduction to Epidemiology

Instructor: Guan-Hua Huang, Ph.D.

E-mail: ghuang@stat.nctu.edu.tw

Class meetings: Wednesday 1:30-4:30 pm

Office hours: Wednesday 10:00am-12:00pm

Course website: ?

Course goals

• To know epidemiologic methods and study design

• Can review published epidemiologic papers and assess the validity of their design and inferences

• To understand how epidemiology is used for identifying the causes of disease

• To be an informed consumer of epidemiological sources of information (journals, Web Sites, government agencies)

Handouts and textbooks

• Handouts will be available on the class website before each class

• The required textbook: Leon Gordis (2000), Epidemiology, 2nd edition, W. B. Saunders Co.

• Supplementary book: David E. Lilienfeld and Paul D. Stolley (1994), Foundations of Epidemiology, 3rd edition, Oxford University Press.

• Get an English-Chinese medical dictionary

Methods of evaluation

• Three homework assignments (30%)• One midterm exam (30%)• One final exam (40%)

Expectations

• Do the background reading for class ahead of time

• Master the specific details of epidemiological strategies and methods

• For assignments, write at a professional level• Please hand-in only typewritten assignments

Course outlines

1. Introduction to epidemiologic approach to health and disease

2. Transmission of disease, occurrence of disease, and investigation of an epidemic

3. Indices of morbidity and mortality 4. Evaluation of diagnostic and screening

tests: validity and reliability 5. Natural history of disease6. Study design: clinical trials, cohort studies

and case-control studies

Course outlines (cont’d)

7. Deriving inferences from epidemiologic studies: association versus causation

8. Interpretation of epidemiologic data: bias, confounding and interaction

9. Genetic epidemiology 10. Psychiatry epidemiology 11. Infectious disease epidemiology 12. Legal, ethical and policy aspects of

epidemiologic investigations

Lecture 1: Epidemiologic approach to health and disease

Reading: Gordis - Chapter 1 Lilienfeld and Stolley - Chapter 1

What is epidemiology?

Epidemiology is the study of the distribution and determinants of disease frequency in human populations

We study

Person

(who)

Place

(where)

Time

(When)

To understand

WHY

Objectives of epidemiology

1. To identify the cause of disease and its risk factors

2. To determine the extent of disease found in the community

3. To study the natural history and prognosis of disease

4. To evaluate new preventative and therapeutic measures

5. To provide a foundation for developing public policy

First: To identify the cause of disease and its risk factors

• This includes field work to identify the causative agents, and know how the disease is transmitted from one person to another.

• SARS a) Causative agent-

coronavirusb) Communicability-

contact and droplet

Second: To determine the extent of disease found in the community

• It involves going to the people.

• Notification of SARS to WHO (Nov. 1, 2002-Jul. 10, 2003):

Ref: www.who.int

Third: To study the natural history and prognosis of disease

• It involves an understanding of the disease biology.

• SARS prognosis:

Ref: Joseph SUNG, WHO SARS Conference

Fourth: To evaluate new preventative and therapeutic measures

• This involves examining the effects of health education and tracking the effects of clinical interventions

• SARS strategy:1. Enhance surveillance system for case

detection2. Comprehensive public education3. Prompt isolation & quarantine4. Environmental hygiene improvement

• SARS prevention: vaccine

Fifth: To provide a foundation for developing public policy

• This involves research -> risk assessment -> risk management

Epidemiology and prevention

A major goal of epidemiology is to identify subgroups in the population who are at high risk for disease. Why?

a) Can identify the specific factors and modify these factors

b) Can direct efforts to populations that are most likely to benefit

Level of prevention

Primary Prevention• Prevention of the occurrence of disease

through:– General health promotion– Specific preventive measures

Secondary Prevention Involves:• Curing disease at the earliest stage possible• Slowing disease progression• Preventing complication• Limiting disability

Epidemiologic reasoning

• Determine whether there is or is not a statistical association between a factor or characteristic and the development of disease

• Derive appropriate inferences regarding a possible causal relationship from the patterns of statistical association which have been found

Epidemiologic approach

1. Initial observation in laboratory or clinical finding

2. Definition of the disease or process by:a) Pathologyb) Common clinical characteristics (sign

and symptoms)c) Specific etiological agent

3. Descriptive epidemiology- identifying associations of disease in relation toa) Timeb) Placec) Persons

Epidemiologic approach (cont’d)

4. Analytical epidemiologya) Identifying associations of disease with

possible etiological factors- genetic and/or environmental

b) Further refine and test hypotheses regarding etiology

5. Experimental epidemiology- evaluate the effectiveness of interventions and preventive and therapeutic programs