Veterinary Epidemiology and Zoonosis

Differences between Case control and Cohort studies

DIFFERENCE BETWEEN CASE-CONTROL AND COHORT STUDY

S.No	Case-control study	Cohort study
1	Proceeds from effect to cause	Proceeds from cause to effect
2	Starts with the disease	Starts with individuals exposed to risk factor or suspected cases
3	Tests whether suspected cause occurs more frequently in those with the disease than among those without the disease.	Tests whether disease occurs more frequently in those exposed than in those not similarly exposed.
4	Usually the first approach to the testing of hypothesis, but also useful for exploratory study	Reserved for testing of precisely formulated hypothesis
5	Involves fewer numbers of subjects	Involves large number of subjects
6	Usually quick results are obtained	Requires long period of time
7	Suitable for study of rare diseases	It does not matter
8	Generally yields estimate of relative risk only (Odds ratio)	Yields incidence rate, relative risk, and attributable risk
9	Relatively inexpensive	Expensive