Are social inequalities as associated with the risk of ischaemic heart disease a result of psychosocial working conditions?

Large social inequalities exist in the risk of ischaemic heart disease (IHD), and they are only partly explained by established cardiovascular disease risk factors. Social class differences in psychosocial working conditions could be important explanatory factors. In a cohort of 1752 employed males, age in years, mean (S.D.): 59.7 (3.5), we investigated the issue. Self-reported psychosocial working conditions examined were: influence on the job, work monotony, work pace, degree of satisfaction with immediate superiors and colleagues, and ability to relax after working hours. One hundred and fourteen men were excluded due to prevalent cardiovascular disease. During the follow-up period (1985/86-1989), 46 men (approx. 3%) suffered an IHD event, 11 events were fatal. Compared with the rest, the highest social class had a relative risk with 95% CI (RR) of IHD of 0.26 (0.06-1.09), an association which was not explained by major potentially confounding or effect modifying factors: smoking, alcohol, physical activity, blood pressure, hypertension, body mass index, serum cholesterol, serum triglycerides, serum HDL, and serum selenium. Including psychosocial factors in the multivariate model had little influence on the estimate, RR = 0.21 (0.05-0.95), and yet there were highly significant differences in psychosocial working conditions between social classes. Neither self-reported influence on the job, work monotony, work pace, degree of satisfaction with immediate superiors and colleagues, nor interactions of the above factors were significantly associated with risk of IHD. However, men who reported that they were incapable of relaxing after working hours had a highly significant approximately threefold increased risk of IHD. We conclude that in middle-aged and elderly males self-reported, i.e. subjective psychosocial working conditions, did not contribute to the explanation of social inequalities in IHD, and that self-reported incapability to relax after work was associated with an increased risk of IHD.