The 'Healthy Worker Effect' produces which systematic error in occupational epidemiology studies?

• A Underestimation of occupational disease risk because the employed population is healthier than the general population used as comparison ✓
• B Overestimation of occupational disease risk because workers are compared to general population
• C Overestimation due to selection of the sickest workers remaining in the workforce
• D Information bias due to workers under-reporting symptoms

Explanation

The Healthy Worker Effect biases occupational studies toward null: employed workers are a self-selected, healthier cohort (they must be well enough to work) compared to the general population which includes the chronically ill, disabled and unemployed. Using general population death/disease rates as the reference underestimates the true occupational risk because the denominator (workers) is systematically healthier. The reverse — sick workers remaining — is called the Healthy Worker Survivor Effect and applies when the most diseased leave earlier, further biasing the estimate toward null.

Reference: Park's Textbook of Preventive and Social Medicine, 27th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

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