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Occupational mortality and morbidity in relation to selective turnover
Scandinavian Journal of Work, Environment & Health
|January 1, 1982
Summary
The healthy worker effect influences occupational studies. Physically demanding jobs, like iron foundries, showed higher mortality than lighter work, despite selection biases.
Area of Science:
- Occupational Health
- Epidemiology
- Sociology
Background:
- The "healthy worker effect" (HWE) is a known bias in occupational cohort studies, particularly affecting physically demanding jobs and influencing life expectancy.
- Health selection impacts employee turnover, complicating the interpretation of mortality and morbidity data in industrial settings.
- Understanding these selection effects is crucial for accurate risk assessment in different occupational environments.
Purpose of the Study:
- To investigate mortality and morbidity across three distinct physical demand levels within the metal industry.
- To compare occupational cohorts (iron foundries, metal product manufacture, electrical device manufacture) with the general male population of Finland.
- To analyze the influence of the "healthy worker effect" and social selection on mortality and turnover.
Main Methods:
- A cohort study of approximately 15,700 men employed between 1950-1976 in three metal industry branches representing heavy, medium, and light physical demands.
- Mortality and disability data were sourced from national registers (1950-1978), with 1,407 deaths recorded over 215,800 person-years.
- A sample of current/former workers and next-of-kin received questionnaires on occupational history, morbidity, and reasons for turnover.
Main Results:
- Standardized mortality ratios (SMRs) were 124 (foundry workers), 92 (metal product workers), and 107 (electrical workers) compared to the general male population.
- The heavy exposure level (foundries) exhibited the highest mortality, while the medium level (metal products) showed the lowest.
- Foundry workers displayed less social selection, whereas metal product workers appeared more socially and health-selected. Economic factors influenced new employee entry.
Conclusions:
- Physically demanding work, exemplified by iron foundries, is associated with higher mortality, underscoring the impact of occupational exposure.
- While survival curves showed minor differences, the HWE and social selection significantly influence cohort characteristics and mortality patterns.
- The study highlights the complex interplay of physical demands, selection biases, and economic factors in occupational health research.