In a case-control study, 200 cases of hepatocellular carcinoma and 400 controls were enrolled. Of the cases, 80 had hepatitis B; of controls, 40 had hepatitis B. The odds ratio is closest to:
- A 4.0
- B 2.0
- C 6.0 ✓
- D 5.3
Correct answer: C. 6.0
Explanation
Constructing the 2×2 table: cases with HBV (a) = 80; cases without HBV (b) = 120; controls with HBV (c) = 40; controls without HBV (d) = 360. OR = (a×d)/(b×c) = (80×360)/(120×40) = 28800/4800 = 6.0. This is a high-yield calculation testing 2×2 table construction and the cross-product (ad/bc) formula. The large OR reflects the strong association between hepatitis B exposure and hepatocellular carcinoma, consistent with hepatitis B being a well-established causative agent.
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.