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The influence of study characteristics on the healthy worker effect: a multiple regression analysis
1Department of Environmental and Occupational Medicine, Medical School, University of Aberdeen, Foresterhill, UK.
Occupational Medicine (Oxford, England)
|October 1, 1996
Summary
The healthy worker effect (HWE) shows lower mortality in employed groups. Study reveals comparison group proximity, exposure hazards, social class, and follow-up loss significantly impact HWE size.
Area of Science:
- Occupational Health
- Epidemiology
- Biostatistics
Background:
- The healthy worker effect (HWE) is characterized by reduced mortality rates observed in employed populations compared to the general population.
- Previous research indicated a low weighted standardized mortality ratio (SMR) for all causes among workers exposed to organic solvents (SMR = 89.5).
Purpose of the Study:
- To investigate the characteristics of occupational cohorts that influence the magnitude of the healthy worker effect.
- To identify key factors associated with variations in the HWE among workers exposed to organic solvents.
Main Methods:
- Analysis of 85 occupational cohorts of workers exposed to organic solvents.
- Multiple regression analysis to examine associations between cohort characteristics and the HWE.
Main Results:
- A closer comparison group was associated with a smaller HWE (p = 0.001).
- More hazardous exposures correlated with a higher SMR (p = 0.02).
- Higher social class (p = 0.02) and increased loss to follow-up (p = 0.04) were linked to a greater HWE.
Conclusions:
- The HWE is significantly influenced by the choice of comparison group, the nature of occupational exposures, socioeconomic status (social class), and the rate of participant attrition (loss to follow-up).
- Observed gender and race differences in HWE are likely due to differential rates of loss to follow-up.