Cigarette smoking and stroke in a cohort of U.S. male physicians.

OBJECTIVE: To examine the association between cigarette smoking and the risk for stroke in men.

DESIGN: Prospective cohort study.

SETTING: Participants in the Physicians' Health Study, a randomized trial of aspirin and beta-carotene among U.S. male physicians.

PATIENTS: 22,071 men, 40 to 84 years of age at entry, free from self-reported myocardial infarction, stroke, and transient ischemic attack; followed for an average of 9.7 years; and classified as never-smokers, current smokers, and former smokers based on self-report.

MEASUREMENTS: Incidence rates of total, ischemic, and hemorrhagic stroke.

RESULTS: With never-smokers as the reference group (relative risk, 1.00), relative risks (adjusted for age and treatment assignment) for total nonfatal stroke (n = 312) were as follows: former smoking, 1.20 (95% CI, 0.94 to 1.53); currently smoking fewer than 20 cigarettes daily, 2.02 (CI, 1.23 to 3.31); and currently smoking 20 or more cigarettes daily, 2.52 (CI, 1.75 to 3.61) (P for trend, < 0.0001). For participants who had total fatal stroke (n = 28), the risk for stroke was not increased with smoking (P > 0.2). In proportional-hazards models that controlled simultaneously for other risk factors, these associations were not materially altered.

CONCLUSIONS: Current but not former cigarette smoking was significantly associated with an increased risk for stroke in men. Smoking may account for a substantial amount of stroke-associated morbidity and mortality.