A prospective cohort study follows 200 exposed and 200 unexposed individuals for 10 years. Forty exposed and 20 unexposed develop the disease. The relative risk is:

• A 1.5
• B 2.5
• C 3.0
• D 2.0 ✓

Explanation

RR = (Incidence in exposed)/(Incidence in unexposed) = (40/200)/(20/200) = 0.20/0.10 = 2.0. The exposed group has twice the risk of developing disease. Relative risk cannot be directly calculated from case-control studies, only from cohort or experimental studies.

Reference: Park's Textbook of Preventive and Social Medicine, 27th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.