Risk factors and their management for stroke prevention: outlook for 1999 and beyond

Stroke is a leading cause of death and morbidity, but incidence rates vary dramatically from one population to another. The reasons for this heterogeneity are being explored in several large-scale epidemiologic studies around the world. Much of the heterogeneity in stroke can be related to the prevalence of risk factors, but some populations have a higher stroke incidence than would be predicted from risk factor levels. Hypertension, including borderline hypertension, is probably the most important stroke risk factor based on degree of risk and prevalence. However, cardiac morbidity, cigarette smoking, diabetes, physical inactivity, and high levels of alcohol consumption are also strongly related to stroke risk. High levels of blood cholesterol and homocysteine may also increase stroke risk. Mortality after stroke is highest within the first 30 days but remains elevated to a degree that depends on the presenting stroke syndrome, stroke subtype, and other co-morbidities. Lacunar strokes have the best short- and long-term prognoses. Strokes due to large-vessel atherosclerosis frequently worsen; these and cardioembolic strokes have the poorest long-term prognosis. The risk for recurrence is also highest within 30 days after a first stroke, depending on the type of infarct, history of hypertension, and blood glucose levels on admission. Predictors of late recurrence include cardiac disease, hypertension, and heavy alcohol use. Only about half of stroke survivors are independent 6 months after a stroke, and quality of life is decreased. Understanding factors that predispose to stroke and determine its outcome will help in the design of acute stroke trials and in prevention programs.