Job control and the risk of incident stroke in the working population in Sweden

Objectives This study estimated the risk of incident stroke according to the level of job control and examined whether the association between job control and the risk of stroke varied as a function of gender. Methods This was a register-based cohort study of nearly 3 million working people (age 30-64 years in 1990) with a 13-year follow-up (1991-2003) for incident stroke (50 114 events). Job control was aggregated to the data by a secondary data source (job-exposure matrix) in 1990. Gender-specific Cox regressions were applied. Results The age- and workhour-adjusted hazard ratio of the lowest versus the highest job control quartile was 1.25 [95% confidence interval (95% CI) 1.17-1.321 for any stroke, 1.33 (95% Cl 1.15-1.55) for intracerebral hemorrhage, and 1.22 (95% Cl 1.14-1.31) for brain infarction among the women, and the corresponding figures for the men were 1.24 (95% Cl 1.21-1.28), 1.30 (95% CI 1.21-1.40), 1.23 (95% C1 1.19-1.28), respectively. Adjustment for education, marital status, and income attenuated these associations to 1.07 (95% CI 1.01-1.14) for any stroke, 1.22 (95% CI 1.04-1.42) for intracerebral hemorrhage, and 1.04 (95% Cl 0.97-1.12) for brain infarction for the women and to 1.08 (95% C1 1.04-1.12), 1.12 (95% Cl 1.03-1.22), 1.08 (95% CI 1.04-1.13), respectively, for the men. Conclusions The relative risk of stroke was higher in low job-control occupations. The association between job control and stroke subtypes varied as a function of gender. The relative risk of intracerebral hemorrhage was highest for the women in low job-control occupations.