Is the association between low job control and coronary heart disease confounded by risk factors measured in childhood and adolescence among Swedish males 40-53 years of age?

OBJECTIVES

Low job control is associated with an increased relative risk of coronary heart disease (CHD). The increased risk seems to be most marked in men under 55 years of age. Adverse social circumstances in childhood have been related to an increased risk of CHD in adulthood. The aim of this study was to investigate the role of differences in CHD risk factors measured in childhood or late adolescence (indicators of social circumstances and negative behaviour), as well as social circumstances in adulthood, for the association between low job control and CHD among Swedish men 40-53 years of age.

METHODS

The study is based on a cohort of 49 323 young Swedish males, born 1949-51. For the study we have used information on childhood environment collected at the 1960 census (when the subjects were 9-11 years of age), negative behavioural factors collected at compulsory conscription for military training among young Swedish men in 1969/70 (when the subjects were 18-20 years of age), data on job control from 1990 (measured indirectly from occupational titles using a job exposure matrix, when the subjects were 39-41 years of age), and follow-up data on CHD hospitalization and mortality between the years 1991 and 2003.

RESULTS

An increased relative risk of CHD (HR = 1.55; 95% CI 1.31-1.84) was found among workers with low job control, compared with workers with high job control. Risk factors for CHD measured in different phases during the life course were strongly associated with level of job control in middle age. In multivariate analyses, taking the factors measured in childhood into consideration and also adjusting for lifestyle factors measured at age 18-20 (smoking, heavy alcohol consumption, and overweight) the increased relative risk of CHD in low control jobs was reduced by 85%. After also adjusting for adult income (according to the 1985 census) no increased relative risks remained.

CONCLUSION

Risk factors for CHD measured already in childhood and adolescence could explain a substantial part of the of the increased risk of CHD and mortality among males 40-53 years of age associated with the measure of low work control used in this study. The results suggest that low job control, measured as in this study, is not a risk factor for CHD among men in this age group.