To the Editor.
—In agreement with Kawachi et al,1 we found cigarette smoking increased the risk of subarachnoid hemorrhage in a population-based, case-control study.2 Considering the 149 male and female cases and the 298 age- and gender-matched controls, the odds ratio (OR) for current heavy smokers (>20 cigarettes/day) was 11.1 (95% confidence interval [CI], 5.0 to 24.9); for current light smokers (<20 cigarettes/day) the OR was 4.1 (95% CI, 2.3 to 7.3); and for former smokers the OR was 1.8 (95% CI, 1.0 to 3.2). The risk was greatest in the 3 hours following smoking a cigarette (OR, 7.0; 95% CI, 3.7 to 13.1) and then decreased, not reaching the risk in those who had never smoked until more than 10 years had passed since the last cigarette.The finding that the risk is greatest in the 3 hours after smoking suggests that a transient factor, such as
Longstreth WT, Nelson LM. Smoking Cessation and Risk of Stroke in Women. JAMA. 1993;269(17):2214. doi:10.1001/jama.1993.03500170043030