What is the primary purpose of a cohort study?

• A. To randomize participants to exposures
• B. To estimate disease prevalence at a single point in time
• C. To investigate associations between exposures and subsequent outcomes by following a defined population over time.
• D. To study genetic mutations only

Answer: (C)

A cohort study follows a defined group over time to examine how exposures relate to future outcomes. This setup preserves temporality—exposure occurs before the outcome—and allows estimation of incidence and measures of association, such as relative risk. It’s especially useful for exploring how a specific exposure influences the development of diseases or other events in real-world populations, and it can be prospective or retrospective. It is not about randomizing exposures, not aimed at measuring prevalence at a single point in time, and is not limited to studying genetic mutations only.