Age-related changes in risk factor effects on the incidence of thromboembolic and hemorrhagic stroke.

We examined the changes in risk factor effects on the incidence of thromboembolic and hemorrhagic stroke as they may occur with age. Findings were based on repeated risk factor measurements at four examinations over a 26-year period in 7589 men in the Honolulu Heart Program. After each examination, 6 years of follow-up were available to assess risk factor effects on the incidence of stroke over a broad range of ages (45-93 years). As compared with normotensive men, the risk of thromboembolic stroke in the presence of hypertension declined from a 7-fold excess in men aged 45 to 54 years to a 1.4-fold excess in men aged > or =75 (P<.001). Adverse effects of diabetes and atrial fibrillation seemed to be equally important across all ages, whereas a protective effect of physical activity increased with age. Except for men with atrial fibrillation, the incidence of thromboembolic stroke increased significantly with age regardless of risk factor status, including men with normal blood pressure (P<.001). Although hemorrhagic events were less common, positive relations with cigarette smoking seemed to strengthen with age, whereas those with hypertension tended to decline. Our findings suggest that strategies for the prevention of stroke may need to account for changes in risk factor effects as they occur with age. Control of diabetes and the encouragement of active lifestyles in the elderly seem to be especially important.