Among asbestos-exposed workers, 60 lung cancer deaths are observed while only 40 would be expected based on age-specific national mortality rates. The standardized mortality ratio (SMR) is:
- A 0.67, indicating reduced risk
- B 150%, indicating a 50% excess ✓
- C 100%, indicating no excess
- D 2.4, indicating a 140% excess
Correct answer: B. 150%, indicating a 50% excess
Explanation
SMR equals observed deaths divided by expected deaths multiplied by 100, here 60 divided by 40 times 100, giving 150%. This means the cohort experiences 50% more deaths than expected. Indirect standardization using national rates is the standard method for occupational cohorts because age-specific rates within the cohort may be unstable. An option such as 0.67 comes from inverting the ratio, a common error.
Reference: Park's Textbook of Preventive and Social Medicine, 27th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
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