Smoking and risk of hemorrhagic stroke in women.

BACKGROUND AND PURPOSE: Several studies established smoking as a risk factor for ischemic stroke and subarachnoid hemorrhage (SAH) in men and women. A recent study added smoking as a risk factor for intracerebral hemorrhage (ICH) in men. In contrast, the impact of smoking on ICH in women is less clear.

METHODS: Prospective cohort study among 39 783 US women participating in the Women's Health Study. Smoking habits and stroke occurrence were self-reported. Stroke cases were confirmed by medical record review. We used Cox proportional hazards model to evaluate the association of smoking with risk of total hemorrhagic stroke, ICH, and SAH. We categorized smoking into never, past, and current smokers of <15 and >or=15 cigarettes per day.

RESULTS: During 9 years of follow up, a total of 70 hemorrhagic strokes occurred, of which 40 were ICH and 29 were SAH. Never smokers and past smokers had equal rates of ICH and SAH. Current smokers of <15 cigarettes per day had a multivariable-adjusted relative risk (RR) of 1.93 (95% CI, 0.75 to 5.02) for total hemorrhagic stroke, 2.15 (95% CI, 0.62 to 7.43) for ICH, and 1.70 (95% CI, 0.38 to 7.60) for SAH. Women who smoked >or=15 cigarettes per day had RR of 3.29 (95% CI, 1.72 to 6.29) for total hemorrhagic stroke, 2.67 (95% CI, 1.04 to 6.90) for ICH, and 4.02 (95% CI, 1.63 to 9.89) for SAH compared with never smokers.

CONCLUSIONS: This prospective study indicates an increased risk of total hemorrhagic stroke, ICH, and SAH in women who are current cigarette smokers. The risk increases with the amount of cigarettes smoked.