4. Epidemiology
"The study of the
distribution
& determinants
of health-related states or events
in specified
populations,
and the application of this study to the
control of health problems".
Epidemiology (epi =upon ,demos =
population)
5.
6. How Distribution
and
Determinants are
studied1) Disease Frequency:
By Rates and Ratios.
2) Distribution of Disease:
By Time, Place & Person.
3) Determinants of Disease:
Identifying underlying cause.
7.
8. Epidemiological studies
Observational .S
(Only measures not
intervene)
Experimental.
S/
Interventions .
S
Descriptive
or
situ: analysis
(occurrence of dis: )
Analytical /
comparative
(Analysis health status
& variables)
Randomize
d clinical
trials
Field Trials
Community
Trials
Cohort/ follow up
Case control
Cross sectional
Ecological
/correlation
9. USES OF DESCRIPTIVE EPID:
It helps to know the Extent / Magnitude of
Dis: (Morbidity & Mortality Rates)
It helps to know distribution of a disease in
the community (Person, Place & Time)
Helps to formulate an etiological
hypothesis.
Helps to plan, organize & implement
curative & preventive services.
15. Typical Study Design: Comm: Health
Survey / Des.S
Typical Study Design: Cohort & Case -
control. S
16. • Simplest form of Observational study.
Cross-sectional study
Based on:
• Single exam: of
• Cross- section of population
• at one point in time / specific point in time
17. Collects data at one point in time
What exists today
More useful for Chronic Diseases.
Cross-sectional study
21. Place (Where)
presence of agents or
vectors
climate
geology
population density
economic development
nutritional practices
medical practices
22. TimeTime distribution:-
Pattern of disease may be described by time of its
occurrence by
Year
Month
season
Week
Day etc
Whether it shows periodic increase or decrease or
it follows constant time trends.
Such clues show about the source or etiology of
dis:
Calendar time
Time since an event
Secular trend
Seasonality
Temporal trends
23.
24. Emphasis on relationship of disease to the host,
the agent and environmental factors.
EPIDEMIOLOGICAL
TRIAD3 essential characteristics that are examined to study the
cause(s) for disease
29. Epidemiologic Activities
…are often framed under the mantle of
descriptive and analytic epidemiology
◦Descriptive epidemiology
(person, place & time)
Demographic distribution
Geographic distribution
Seasonal patterns etc.
Frequency of disease patterns
◦Useful for:
Allocating resources
Planning programs
Hypotheses development
30. Epidemiologic Activities
Analytic epidemiology
built around the analysis of the
relationship between two items
Exposures
Effects (disease)
◦looking for determinants or
possible causes of disease
◦useful for
hypothesis testing