Prevalence of risk factors for aneurysmal subarachnoid haemorrhage: results of a Japanese multicentre case control study for stroke.

The pathogenesis of subarachnoid haemorrhage (SAH) is still unclear. To evaluate the risk factors for aneurysmal SAH, we conducted a multicentre case control study. All aneurysms were detected by cerebral angiography and the patients with SAH other than ruptured aneurysms were excluded. Information on past medical histories and other possible risk factors for SAH were assessed by a structured questionnaire. Data on the total 127 pairs (59 male and 68 female) were analysed. In a univariate analysis, family history of SAH [odds ratio (OR) 9.45], systemic hypertension (OR 2.65), cigarette smoking (OR 2.54) and regular alcohol consumption (OR 1.92) were significant risk factors for aneurysmal SAH. Heavy alcohol consumption (>350 g ethanol/week) was significant (OR 3.22), whereas light consumption (=<350 g/week) did not to increase the risks (OR 0.95). Both light (<20 cigarettes/day, OR 2.44) and heavy smoking (>=20 cigarettes/day, OR 2.72) were associated with an increased risk of SAH. In a multivariate analysis, after adjustment for other risk factors, family history of SAH, cigarette smoking and hypertension remained significant.