Occupational social class and disability retirement among municipal employees--the contribution of health behaviors and working conditions.

OBJECTIVES: The mechanisms through which a low socioeconomic position leads to disability retirement are not yet established. We examined, on the one hand, the associations between occupational social class and disability retirement due to all causes, musculoskeletal diseases, and mental disorders and, on the other hand, the contribution of health behaviors and working conditions to these associations.
METHODS: Middle-aged municipal employees from the Helsinki Health Study cohort baseline surveys in 2000-2002 (N=6516) were followed up until the end of 2010 for disability retirement. Retirement data were obtained from the registers of the Finnish Centre for Pensions and social class and covariates from the baseline surveys. Social class was categorized into managers and professionals, semi-professionals, routine non-manual employees, and manual workers. Cox regression analysis was used to calculate hazard ratios and their 95% confidence intervals.
RESULTS: The risk of disability retirement was generally higher among those in lower social classes with a strong gradient for all causes, an even stronger gradient for musculoskeletal diseases, and a weaker non-linear association for mental disorders. These associations were largely mediated through physical workload among both women and men and hazardous exposures particularly among men. In mental disorders, job control also mediated the association. Strenuous desktop work and job demands widened the social class differences particularly among men and in mental disorders. The contribution of health behaviors was modest.
CONCLUSIONS: Improvements particularly in the physical working conditions but also the job control of those in lower social classes are likely to reduce socioeconomic differences in disability retirement.