Do psychosocial job resources buffer the relation between physical work demands and coronary heart disease? A prospective study among men.

Purpose: Increasing evidence shows the detrimental impact of high physical work demands for cardiovascular health and mortality. The aim of this study was to investigate the buffering effects of social support at work and job control in the relation between physical work demands and incidence of coronary events.
Methods: The study included 14,337 middle-aged men free from coronary heart disease (CHD) at baseline. The sample consisted of a mixed occupational group recruited within 18 organizations from the manufacturing, service, and public sector. Data were collected through standardized questionnaires and clinical examinations. The incidence of clinical coronary events was monitored during a mean follow-up time of 3.15 years. Multilevel Cox proportional hazard regression modeling was used, adjusting for socio-demographic and classical coronary risk factors.
Results: Social support at work buffered the impact of physical work demands on CHD risk: Only among workers with low social support at work did physical work demands significantly increase the risk for CHD incidence (fully adjusted HR 2.50: 95 % CI 1.13-5.50), while this harmful effect completely disappeared in case of high level of workplace social support (fully adjusted HR 0.40; 95 % CI 0.09-1.70). No interaction or buffering effect with job control was observed.
Conclusions: The results of our study suggest that supportive relationships at work may be a useful resource for reducing the cardiovascular risk associated with physical work demands in men. Future studies are needed to confirm this moderating role of workplace social support and to unravel the underlying mechanisms.