cohort study epidemioloy chapter

1. COHORT STUDY
PRESENTED BY
DR.ANJALATCHI MUTHUKUMARAN
VICE PRINCIPAL
ERA COLLEGE OF NURSING

3. The word cohort is derived from the latin word “
COHORTS” meaning an enclosure, company, or
crowd.
In Roman times a cohort was a body of 300-600
infantry.
In epidemiological terms the cohort is a group of
people with something in common , usually an
exposure or involvement in a defined population
group.

4. Cohort is a group of people with common
characteristics , e.g birth cohort ,marriage
cohort.

5. Cohort study is also known as a longitudinal
study ,incidence study and forward looking study.
Cohort study is also called incidence studies ,are
designed to measures the exposure and outcome
in the context of time .

6. Cohorts are identified prior to appearance of
disease under investigation .
The study groups are observed over a period of
time to determine the frequency of disease along
them.
The study proceeds from cause to effects.

7.  There is good evidence of an association
between exposure and disease , from other
studies.
Exposure is rare .
Attrition of study population can be
minimized.
Sufficient fund is available.

8. Prospective study .
Retrospective study.
Combined –amphi.

9. 1.Selection of study population.
2.Obtaining data on exposure.
3.Selection of comparison group .
4. Follow up.
5. Analysis.

10. Temporality can established .
Incidence can be calculated .
Several possible outcomes related to
exposure can be studied simultaneously.
Provide direct estimated of risk.
Allows the conclusion of cause effect
relationship.

11. Large population is needed.
Not suitable for rare diseases.
It is time consuming and expensive.
Certain administrative problems like loss of staff,
loss of funding and extensive record keeping are
common.
Study itself may alter people’s behavior.