Stroke Subtype Classification to Mechanism-Specific and Undetermined Categories by TOAST, A-S-C-O, and Causative Classification System

Abstract

Background and Purpose— Reliable etiologic classification of ischemic stroke may enhance clinical trial design and identification of subtype-specific environmental and genetic risk factors. Although new classification systems (Causative Classification System [CCS] and ASCO [A for atherosclerosis, S for small vessel disease, C for cardiac source, O for other cause]) have been developed to improve subtype assignment, few comparative data exist from large studies. We hypothesized that both CCS and ASCO would reduce the proportion of patients classified as cause undetermined compared with the Trial of ORG 10172 in Acute Stroke Treatment (TOAST) scheme in a large population-based stroke study. Methods— A single rater classified all first-ever ischemic strokes in the North Dublin Population Stroke Study, a population-based study of 294 529 North Dublin residents. Published algorithms for TOAST, CCS, and ASCO were applied. Results— In 381 first-ever ischemic stroke patients, CCS assigned fewer patients as cause ...