Risk factors for aneurysmal subarachnoid hemorrhage in patients in Izumo City, Japan

Object. The annual incidence of aneurysmal subarachnoid hemorrhage (SAH) in Izumo City, Japan, appears to be the highest rate among those reported; therefore the author investigated the risk factors for SAH in patients in this city. Methods. A case-control study of 247 patients (108 men and 139 women with ages ranging from 28–96 years) with aneurysmal SAH was conducted in Izumo between 1980 and 1998. Hypertension, diabetes mellitus, heart disease, liver disease, cigarette smoking, alcohol consumption, and serum levels of total cholesterol, aspartate aminotransferase, alanine aminotransferase, and urea nitrogen were assessed as possible risk factors for SAH by using conditional logistic regression. After adjustment for other risk factors, results of multivariate analysis showed that hypertension was the most powerful risk factor, regardless of age and sex. The odds ratio for hypertension was higher in women than in men. The second greatest risk factors were cigarette smoking in those 59 years of age or younger and in men and hypercholesterolemia in those 60 years of age or older and in women. Among individuals 60 years of age or older and among women, diabetes mellitus and heart disease were inversely associated with the risk of SAH. When analyses were performed in 219 cases of confirmed ruptured cerebral aneurysm, very similar results were obtained. Conclusions. Among patients in Izumo, hypertension was the most notable risk factor for aneurysmal SAH, regardless of age and sex, followed by cigarette smoking in younger men and hypercholesterolemia in older women. In older women, diabetes mellitus and heart disease decreased the risk of SAH.