In a village of 1 lakh population, among 2,000 exposed to smoking, 20 developed lung cancer and among 8,000 unexposed people, 8 developed lung cancer. What is attributable risk-

This is a coho study. Attributable risk = (incidence in exposed -incidence in nonexposed) /incidence in exposed *100 Incidence in exposed=20/2000 Incidence in nonexposed=8/8000 Attributable risk=(0.01-0.001/.01)*100 = 90% 90% of lung cancer among smokers can be attributed to their smoking Ref: Parks textbook of preventive and social medicine, 23rd Edition Pg no: 78