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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 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<.001). Cardioembolic stroke (C1) was more frequent (22.2 vs. 31%; P<.001). No differences between unusual cause of stroke and other potential causes (O1) were observed. Some degree of atherosclerosis was present in 53.5% of patients (A1, A2, or A3); 65.5% showed markers of small vessel disease (S1, S2, or S3), and 74.9% showed signs of cardioembolism (C1, C2, or C3). Fewer patients in the group without scores of 1 or 2 for any of the A-S-C-O phenotypes were identified as having a stroke of undetermined cause (46.6 vs. 29.2%; P<.001). The agreement between the 2 classifications ranged from κ<0.2 (small vessel and S1) to 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.

Original publication




Journal article



Publication Date





417 - 424


A-S-C-O classification, Aetiological classification, Clasificación A-S-C-O, Clasificación del Grupo de Estudio de Enfermedades Cerebrovasculares de la Sociedad Española de Neurología, Clasificación etiológica, Classification by the Spanish Society of Neurology‘s Cerebrovascular Disease Study Group, Ictus de causa indeterminada, Stroke of undetermined cause, Aged, Aged, 80 and over, Atherosclerosis, Brain Ischemia, Cerebral Small Vessel Diseases, Female, Humans, Intracranial Embolism, Ischemic Attack, Transient, Male, Middle Aged, Spain, Stroke