A prospective cohort study of employment status and mortality from circulatory disorders among Japanese workers

This study prospectively examined the association between employment status (employed or self-employed) and the risk of death from circulatory diseases among Japanese workers. A baseline survey was conducted between 1988 and 1990 among 110,792 inhabitants of 45 areas. Follow-up surveys were conducted annually and causes of death were identified from death certificates. Analysis was restricted to 25,945 individuals (15,434 male and 10,511 female) with ages ranging from 40 to 59 years. These subjects were employed or self-employed at the time of recruitment. The risks of self-employment for death due to circulatory system disease, ischemic heart disease and cerebrovascular disease were estimated using the Cox proportional hazards model. During the 10-year follow-up period (151,817 and 104,870 person-years for males and females, respectively), 720 male and 193 female deaths were recorded. No significant differences were detected between the employed and self-employed workers in the total death risk, or the risk of death from ischemic heart disease. However, self-employed men showed a significantly lower risk of death from cerebrovascular disease compared with employed men (relative risk=0.58; 95% confidence interval=0.35, 0.97). Our findings suggest that employed men are at increased risk of death from cerebrovascular disease compared with self-employed men.