Background and purpose: Smoking is an established risk factor for ischemic stroke and subarachnoid hemorrhage (SAH), but the impact of smoking on intracerebral hemorrhage (ICH) is less clear.
Methods: Prospective cohort study among 22,022 US male physicians participating in the Physicians' Health Study. Incidence of stroke was measured by self-report and confirmed by medical record review. We used Cox proportional-hazards models to evaluate the association of smoking with risk of total hemorrhagic stroke, ICH, and SAH. We categorized smoking into 4 groups: never, past, or current smokers of <20 or of >or=20 cigarettes per day.
Results: During 17.8 years of follow-up, 108 ICHs and 31 SAHs occurred. Never smokers and past smokers had equal rates of ICH and SAH. Current smokers of <20 cigarettes per day had multivariable-adjusted relative risks of 1.65 (95% CI, 0.61 to 4.50) for total hemorrhagic stroke, 1.60 (95% CI, 0.50 to 5.07) for ICH, and 1.75 (95% CI, 0.24 to 13.09) for SAH when compared with never smokers. Current smokers of >or=20 cigarettes had relative risks of 2.36 (95% CI, 1.38 to 4.02) for total hemorrhagic stroke, 2.06 (95% CI, 1.08 to 3.96) for ICH, and 3.22 (95% CI, 1.26 to 8.18) for SAH when compared with never smokers.
Conclusions: This prospective study suggests an increased risk of total hemorrhagic stroke, ICH, and SAH in current cigarette smokers with a graded increase in risk that depended on how many cigarettes were smoked. The effect of smoking on ICH is of about the same magnitude as the effect of smoking on ischemic stroke. Our results add to the multiple health benefits that can be accrued by abstaining from cigarette smoking.