Occupational class and incidence rates of cardiovascular events in middle aged men in Japan.

We investigated whether occupational class affects the incidence of cardiovascular events in Japanese factory workers. We prospectively evaluated 1,794 male workers aged 40-59, including 632 non-manual and 1,162 manual workers, employed in a metal products factory in Japan. The hazard ratios of stroke, myocardial infarction (MI) and cardiovascular events (combined stroke, MI and sudden cardiac death) for manual workers were compared with non-manual workers as estimated by the Cox proportional hazards regression model. Among the 1,794 workers, there were 60 cardiovascular events (32 cases of stroke, 23 cases of MI and 5 cases of sudden cardiac death) with an incidence rate of 3.14 per 1,000 person-years for cardiovascular events; 1.68 for stroke and 1.20 for MI. Blood pressure and HbA1c significantly increased the risk of stroke. Body mass index and total cholesterol significantly increased the risk of MI. However, occupational class was determined not to be a risk factor for cardiovascular events. The hazard ratios of stroke, MI and cardiovascular events for manual workers compared with non-manual workers were 0.97 (95%CI, 0.45-2.08), 0.73 (95%CI, 0.30-1.79) and 0.92 (95%CI, 0.53-1.61), respectively. Our study did not reveal significant occupational class inequalities in the rate of cardiovascular events. These findings are not in accordance with studies from other industrialized countries.