Supplementary Material for: Towards Understanding the Cause of Stroke in Young Adults Utilising a New Stroke Classification System (A-S-C-O) Cotter P.E. Belham M. Martin P.J. 10.6084/m9.figshare.5123011.v1 https://karger.figshare.com/articles/dataset/Supplementary_Material_for_Towards_Understanding_the_Cause_of_Stroke_in_Young_Adults_Utilising_a_New_Stroke_Classification_System_A-S-C-O_/5123011 <i>Background:</i> Stroke in younger people is relatively common and frequently unexplained. While understanding of the causes of young stroke has improved, there remains uncertainty over the role of low-risk lesions such as a patent foramen ovale (PFO). The TOAST criteria are often used to describe stroke aetiology, but in younger people in whom PFOs are frequent, there is a very high proportion of cases attributed to cardiac embolism. The impact of using the newer A-S-C-O criteria on stroke aetiology was investigated. <i>Methods:</i> Consecutive patients with ischaemic stroke were investigated and categorised by the TOAST and ASCO1 criteria. Stroke aetiology was presented and compared by the different classification systems. <i>Results:</i> Of the 106 ischaemic stroke cases, by TOAST 6% were ‘large artery atheroma’, 11% ‘small vessel occlusion’, 28% ‘cardioembolic’, 22% ‘other determined cause’ and 33% ‘undetermined cause’. The vascular territory and associated causes are presented. With the ASCO1 criteria, there were more cases of unclassified stroke (51.9 vs. 34.0%; p < 0.001) and fewer cases of cardiac embolism. Kappa ranged from 0.5 for ‘undetermined aetiology’ to 1.0 for both ‘large artery atheroma’ and ‘other determined aetiology’. Younger cases (<45 years) were less likely to be either ‘large artery atheroma’ or ‘small vessel occlusion’. <i>Conclusion:</i> Using the ASCO criteria, more patients fall into the undetermined group which more accurately reflects our current uncertainty regarding the pathogenic relevance of PFOs in this age group. 2011-12-14 00:00:00 Stroke Cerebral infarction Young adult Etiology