In a case-control study of bladder cancer, 60 cases and 40 controls had occupational exposure to aromatic amines, while 30 cases and 70 controls were unexposed. The odds ratio is:
- A 2.5
- B 4.0
- C 3.5 ✓
- D 1.75
Correct answer: C. 3.5
Explanation
OR = (a×d)/(b×c) = (60×70)/(40×30) = 4200/1200 = 3.5. This means exposed individuals have 3.5 times the odds of developing bladder cancer compared to unexposed. Options A, C, and D result from arithmetic errors in cross-multiplication.
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.