A nested case-control study was conducted within a prospective cohort of factory workers. Cases of bladder cancer (n=80) were identified and 320 controls were selected from the same cohort. Blood samples collected at baseline were analyzed. The PRIMARY advantage of this design over a conventional case-control study is:
- A Eliminates recall bias and allows temporal relationship to be established ✓
- B Provides incidence rates directly
- C Increases statistical power more than a standard cohort study
- D Avoids selection bias entirely because controls are population-based
Correct answer: A. Eliminates recall bias and allows temporal relationship to be established
Explanation
The nested case-control study is embedded within a pre-existing cohort where exposure data (biological specimens, questionnaires) were collected before disease onset. This eliminates recall bias because subjects provided information before knowing their disease status, and it establishes temporality because exposure precedes outcome. Controls are drawn from the same cohort risk set, substantially reducing selection bias but not eliminating it entirely. Incidence rates are not directly calculable from a case-control design, even nested.
Reference: Park's Textbook of Preventive and Social Medicine, 27th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
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