Aims: There is no consensus definition for minor and major stroke in trials comparing CAS vs. CEA. In this study the patients of our large single-centre CAS registry suffering a procedure-related stroke were categorised as minor or major stroke according to study-specific definitions.
Methods and results: A board-certified neurologist examined nearly all patients (99%) pre- and post-procedurally, and once again in case of a subsequent neurological deficit. To objectify the deficits the NIHS Scale and modified Rankin Scale (mRS) were used. To compare the difference of the rates of minor and major strokes according to each definition, Fleiss' Kappa and Cohen's Kappa Test were used, as appropriate. Up to 30 days, 34 (3.6%) neurological events in 947 procedures lasting >24 hours (=stroke) occurred. According to our definition (major stroke: symptoms lasting >30 days, NIHSS ≥4 and/or mRS ≥3), 15 (1.6%) sustained a major and 19 (2%) a minor stroke. The comparison of all definitions of stroke resulted in a substantial agreement (Fleiss' Kappa=0.73). The stroke rates depending on available definitions were as follows: our centre 19 minor/15 major strokes, CREST 15/18 (1 n.a.), Yadav et al 14/20, Bamford et al 18/13 (3 n.a.), Post et al 18/13 (3 n.a.), SPACE 17/17, ICSS 22/11 (1 n.a.).
Conclusions: Study-specific definitions for minor and major strokes lead to significantly different rates of stroke. Therefore, study-specific definitions should be respected comparing the results of each trial. A standard definition for minor and major stroke should be used in future trials.