A prospective cohort study enrolls healthy individuals and finds that among 500 smokers followed for 10 years, 80 developed lung cancer, while among 500 non-smokers, 10 developed lung cancer. Calculate the attributable risk percent (attributable fraction) among exposed:
- A 62.5%
- B 87.5% ✓
- C 75.0%
- D 93.0%
Correct answer: B. 87.5%
Explanation
Incidence in smokers = 80/500 = 0.16; incidence in non-smokers = 10/500 = 0.02. Attributable risk = 0.16 − 0.02 = 0.14. Attributable risk percent (ARP) = (AR/incidence in exposed) × 100 = (0.14/0.16) × 100 = 87.5%. This means 87.5% of lung cancer in smokers is attributable to smoking.
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.