The role of lifestyle factors in the etiology of stroke. A population-based case-control study in Perth, Western Australia.

BACKGROUND AND PURPOSE We sought to examine risk factors for all strokes and for ischemic stroke and primary intracerebral hemorrhage separately. METHODS This was a population-based case-control study. Each case subject meeting World Health Organization criteria for stroke (n = 536) from a population-based register of acute cerebrovascular events compiled in Perth, Western Australia, in 1989 to 1990 was matched for age and sex with up to five control subjects drawn from the same geographical area. Objective confirmation of the type of stroke was available from computed tomography, magnetic resonance imaging, or necropsy for 86% of the case subjects. Data on medical history and lifestyle factors were collected from case and control subjects by interview of the subject or a proxy informant. RESULTS Current smoking, consumption of meat more than four times weekly, and a history of hypertension or intermittent claudication were each associated with increased risk in multivariate models for all strokes and for all first-ever strokes. Consumption of 1 to 20 g/d alcohol in the preceding week was associated with a significant reduction in the risk of all strokes, all ischemic strokes, and of primary intracerebral hemorrhage, while eating fish more than two times per month appeared to protect against first-ever stroke and against primary intracerebral hemorrhage. Diabetes mellitus was associated with a significantly increased risk of ischemic stroke but a decreased risk of hemorrhagic stroke. CONCLUSIONS Risk factors for ischemic and hemorrhagic stroke are not exactly the same. Changes in lifestyle relating to tobacco and diet might make important contributions to further reductions in the incidence of stroke.