Job control, job demands, or social class? The impact of working conditions on the relation between social class and health.

BACKGROUND The aim of the study was to investigate (1) how much of the association between health and social class is accounted by psychosocial working conditions, and (2) whether health is related to working conditions after controlling for social class. METHODS The data derive from the surveys of the Helsinki health study, collected in 2000, 2001, and 2002 from 40-60 year old employees working for the City of Helsinki (n=8970, response rate 67%). The study measured occupation based social class and Karasek's demand-control model. The health outcomes were self rated health as less than good and limiting longstanding illness. Age adjusted prevalence percentages and fitted logistic regression models were calculated. RESULTS The individual effects of social class and psychosocial working conditions on self rated health and limiting longstanding illness were strong among both men and women. The relation between social class and both health outcomes considerably attenuated when job control was controlled for, but was reinforced when controlling for job demands. Controlling for both job control and job demands attenuated the relation between social class and self rated health and limiting longstanding illness among women, however, was reinforced among men. CONCLUSIONS A substantial part of the relation between social class and health could be attributed to job control, however, job demands reinforced the relation. Although the effect of social class is mediated by psychosocial working conditions, both social class and working conditions were related to health after mutual adjustments.