Stroke in South America: a systematic review of incidence, prevalence, and stroke subtypes.

BACKGROUND AND PURPOSE Stroke is a leading cause of mortality and disability in South America because of an increase in life expectancy and changes in the lifestyle of the population. Because epidemiological and clinical characteristics of stroke vary according to regional factors, we need to know the peculiarities of stroke on this continent. METHODS We performed a systematic review of articles on stroke in South America, with emphasis on those providing information on the incidence and prevalence of stroke (community-based studies) and the pattern of stroke subtypes (hospital-based studies). RESULTS Seven papers provided information on stroke epidemiology; 11 gave data on the pattern of stroke subtypes. Community-based studies showed crude stroke prevalence rates ranging from 1.74 to 6.51 per 1000 and annual incidence rates from 0.35 to 1.83 per 1000. Hospital-based stroke registries consistently reported a high frequency of intracranial hemorrhages, which accounted for 26% to 46% of all strokes. Among patients with cerebral infarctions, intracranial atherosclerotic lesions and small-vessel disease have been common pathogenic mechanisms underlying the stroke. In most studies, hypertensive arteriolopathy was the most common cause of both infarctions and hemorrhages. CONCLUSIONS Stroke has been poorly studied in South America. Available data suggest that the prevalence and incidence of stroke are lower than in developing countries. The pattern of stroke subtypes seems to be different from that reported in other regions of the world, with a higher frequency of cerebral hemorrhages, small-vessel disease, and intracranial atherosclerotic lesions. Such differences may be related to genetic, environmental, or sociocultural factors and to differences in the control of stroke risk factors.