Transcript lect1(091003)

Introduction to Epidemiology
Instructor: Guan-Hua Huang, Ph.D.
E-mail: [email protected]
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 disease
6. 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
Person
(who)
We study
Place
(where)
To understand
WHY
Time
(When)
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 agentcoronavirus
b) Communicabilitycontact 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
detection
2. Comprehensive public education
3. Prompt isolation & quarantine
4. 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) Pathology
b) Common clinical characteristics (sign
and symptoms)
c) Specific etiological agent
3. Descriptive epidemiology- identifying
associations of disease in relation to
a) Time
b) Place
c) Persons
Epidemiologic approach (cont’d)
4. Analytical epidemiology
a) 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