Epidemiology of Ischemic Stroke Subtypes According to TOAST Criteria

Abstract

Background and Purpose — The purpose of this study was to determine the incidence, recurrence, and long-term survival rates of ischemic stroke subtypes by a mechanism-based classification scheme (Trial of ORG 10172 in Acute Stroke Treatment, or TOAST). Methods — We identified all 583 residents of the city of Erlangen, Bavaria, Germany, with a first ischemic stroke between 1994 and 1998. Multiple overlapping sources of information were used to ensure completeness of case ascertainment. The cause of ischemic stroke was classified according to the TOAST criteria. Patients were followed up at 3 months and 1 and 2 years after stroke onset. Results — The age-standardized incidence rates for the European population (per 100 000) regarding ischemic stroke subtypes were as follows: cardioembolism, 30.2 (95% CI 25.6 to 35.7); small-artery occlusion, 25.8 (95% CI 21.5 to 30.9); and large-artery atherosclerosis, 15.3 (95% CI 12 to 19.3). When age-adjusted to the European population, the incidence rate for large-artery atherosclerosis was more than twice as high for men than for women (23.6/100 000 versus 9.2/100 000). Two years after onset, patients in the small-artery occlusion subgroup were 3 times more likely to be alive than those with cardioembolism. Ischemic stroke subtype according to the TOAST criteria was a significant predictor for long-term survival, whereas subtype was not a significant predictor of long-term recurrence up to 2 years, both before and after adjustment for age and sex. Conclusions — Epidemiological observational studies that possess wide access to appropriate diagnostic technologies and apply standardized etiologic classifications provide a much better understanding of underlying risk factors for initial stroke, recurrence, and mortality.