Epidemiology

3. Types of epidemiological studies

3.2 Analytic studies

3.2.1 Observational studies

B. Cohort studies

Figure 8: Principle of a cohort study (prospective observation)

Subjects are selected according to the presence of the disease (cases) or absence of the disease (controls).

The subjects are observed, usually prospectively, for a determined period of time or until the onset of the illness.

The subjects are examined during the follow-up time.

Example of an analytic study that is an observational study > cohort study