Background: Few prospective data are available to evaluate potential risk factors of subarachnoid hemorrhage among the Japanese, although several prospective studies conducted in the United States and in Europe have shown a positive relationship between alcohol intake and the risk of subarachnoid hemorrhage.
Methods: A 9.4 year follow-up study was conducted on 12,372 men and women age 40 to 69 years who had no history of stroke, in six communities in Japan. The incident cases of subarachnoid hemorrhage were confirmed with computed tomography findings and/or clinical findings. Alcohol intake and other cerebrovascular risk factors were measured at the baseline examination. A Cox proportional hazard analysis was used to estimate the relative risks and 95% confidence intervals of the incidence of subarachnoid hemorrhage.
Results: During the follow-up assessment, 71 cases of subarachnoid hemorrhages occurred. For men, heavy drinking appeared to be an independent risk factor for subarachnoid hemorrhage; multivariate-adjusted relative risk was 4.3 (95% confidence interval [CI]: 1.1-16.8; p = 0.04). Among women, no excess risk was found for heavy drinking, probably due to the small number of heavy drinkers (n = 15). The combination of heavy drinking with smoking or hypertension increased the risk of subarachnoid hemorrhage substantially for men; the multivariate-adjusted relative risk was 6.0 (95% CI: 1.8-20.1;p = 0.004) for heavy drinking smokers and 13.0 (95% CI: 3.9-43.9; p < 0.001) for heavy drinking hypertensives.
Conclusions: A reduction in alcohol intake, smoking cessation, and control of hypertension are important in preventing subarachnoid hemorrhage among Japanese men.