In a prospective cohort study of lung cancer incidence, healthy worker effect is a concern. This bias leads to:
- A Overestimation of occupational cancer risk because workers are sicker than the general population
- B Overestimation of incidence rate because workers have more access to diagnosis
- C Underestimation of occupational cancer risk because employed workers are healthier than the general population at baseline ✓
- D Underestimation of prevalence because prevalent cases are excluded at enrolment
Correct answer: C. Underestimation of occupational cancer risk because employed workers are healthier than the general population at baseline
Explanation
The healthy worker effect is a selection bias in occupational cohort studies: employed workers are generally healthier than the general population at study entry because severely ill individuals are excluded from employment. When comparing worker cancer rates to general population rates, the worker cohort appears healthier (lower mortality/morbidity), leading to underestimation of true occupational risks. This bias is addressed by using an internal comparison group (unexposed workers in the same industry) rather than general population comparisons.
Reference: Park's Textbook of Preventive and Social Medicine, 27th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
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