Risk factors for subarachnoid hemorrhage

OBJECTIVE: Cigarette smoking has been demonstrated to increase the risk of subarachnoid hemorrhage (SAH). Whether cessation of smoking decreases this risk remains unclear. We performed a case-control study to examine the effect of smoking and other known risk factors for cerebrovascular disease on the risk of SAH. METHODS: We reviewed the medical records of all patients with a diagnosis of SAH (n = 323) admitted to Johns Hopkins Hospital between January 1990 and June 1997. Controls matched for age, sex, and ethnicity (n = 969) were selected from a nationally representative sample of the Third National Health and Nutrition Examination Survey. We determined the independent association between smoking (current and previous) and various cerebrovascular risk factors and SAH by use of multivariate logistic regression analysis. A separate analysis was performed to determine associated risk factors for aneurysmal SAH. RESULTS: Of 323 patients admitted with SAH (mean age, 52.7 ± 14 yr; 93 were men), 173 (54%) were hypertensive, 149 (46%) were currently smoking, and 125 (39%) were previous smokers. In the multivariate analysis, both previous smoking (odds ratio [OR], 4.5; 95% confidence interval [Cl], 3.1-6.5) and current smoking (OR, 5.2; 95% Cl, 3.6-7.5) were significantly associated with SAH. Hypertension was also significantly associated with SAH (OR, 2.4; 95% Cl, 1.8-3.1). The risk factors for 290 patients with aneurysmal SAH were similar and included hypertension (OR, 2.4; 95% Cl, 1.8-3.2), previous smoking (OR, 4.1; 95% Cl, 2.7-6.0), and current smoking (OR, 5.4; 95% Cl, 3.7-7.8). CONCLUSION: Hypertension and cigarette smoking increase the risk for development of SAH, as found in previous studies. However, the increased risk persists even after cessation of cigarette smoking, which suggests the importance of early abstinence from smoking.