Aetiological classification of ischaemic strokes: Comparison of the new A-S-C-O classification and the classification by the Spanish Society of Neurology's Cerebrovascular Disease Study Group

Abstract Introduction The A-S-C-O classification may be better than other methods for classifying ischaemic stroke by aetiology. Our aims are to describe A-S-C-O phenotype distribution (A: atherosclerosis, S: small vessel disease, C: cardiac source, O: other causes; 1: potential cause, 2: causality uncertain, 3: unlikely to be a direct cause although disease is present) and compare them to the Spanish Society of Neurology's Cerebrovascular Disease Study Group (GEECV/SEN) classification. We will also find the degree of concordance between these classification methods and determine whether using the A-S-C-O classification delivers a smaller percentage of strokes of undetermined cause. Methods We analysed those patients with ischaemic stroke admitted to our stroke unit (SU) in 2010 with strokes that were classified according to GEECV/SEN and A-S-C-O criteria. Results The study included 496 patients. The percentages of strokes caused by atherosclerosis and small vessel disease according to GEECV/SEN criteria were higher than the percentages for potential atherosclerotic stroke (A1) (14.1% vs. 11.9%; P  = .16) and potential small vessel stroke (S1) (14.3% vs. 3%; P P P The agreement between the 2 classifications ranged from κ κ  > 0.8 (unusual causes and O1). Conclusion Our results show that GEECV/SEN and A-S-C-O classifications are neither fully comparable nor consistent. Using the A-S-C-O classification provided additional information on co-morbidities and delivered a smaller percentage of strokes classified as having an undetermined cause.