Mortality and risk factors for stroke and its subtypes in a cohort study in Japan

Objective.To estimate stroke mortality and evaluate risk factors for total stroke deaths and its two principal subtypes in a cohort study in Japan.Methods.A total of 9651 subjects aged 40 or over and free of stroke were analyzed in a cohort study conducted in Fukuoka Prefecture, Japan. The follow-up period was from 1986 to 2003. Mortality rate per 100,000 person-years of stroke was estimated. The Cox proportional hazards model was used to estimate the hazard ratios and 95% confidence interval.Results.A total of 226 stroke deaths were recorded during 132,972 years of follow-up. Among these, 47 were intracerebral hemorrhage and 109 were cerebral infarction. Stroke mortality rates were 209.4 per 100,000 person-years in males, and 140.5 in females. The results showed that advanced age, male gender, low body mass index (BMI), history of diabetes, hypertension, and transfusion were associated with an increased risk of mortality from total stroke.Conclusion.We confirmed that advanced age, male gender, low BMI, history of diabetes, history of hypertension and history of transfusion were associated with an increased risk of total stroke mortality. In addition, the magnitude of these associations differed between the two principal stroke subtypes.