title: Early stroke risk and ABCD2 score performance in tissue- vs time-defined TIA: a multicenter study.
abstract: OBJECTIVE
  Stroke risk immediately after TIA defined by time-based criteria is high, and prognostic scores (ABCD2 and ABCD3-I) have been developed to assist management. The American Stroke Association has proposed changing the criteria for the distinction between TIA and stroke from time-based to tissue-based. Research using these definitions is lacking. In a multicenter observational cohort study, we have investigated prognosis and performance of the ABCD2 score in TIA, subcategorized as tissue-positive or tissue-negative on diffusion-weighted imaging (DWI) or CT imaging according to the newly proposed criteria.
  
  
  METHODS
  Twelve centers provided data on ABCD2 scores, DWI or CT brain imaging, and follow-up in cohorts of patients with TIA diagnosed by time-based criteria. Stroke rates at 7 and 90 days were studied in relation to tissue-positive or tissue-negative subcategorization, according to the presence or absence of brain infarction. The predictive power of the ABCD2 score was determined using area under receiver operator characteristic curve (AUC) analyses.
  
  
  RESULTS
  A total of 4,574 patients were included. Among DWI patients (n = 3,206), recurrent stroke rates at 7 days were 7.1%(95% confidence interval 5.5-9.1) after tissue-positive and 0.4% (0.2-0.7) after tissue-negative events (p diff < 0.0001). Corresponding rates in CT-imaged patients were 12.8% (9.3-17.4) and 3.0% (2.0-4.2), respectively (p diff < 0.0001). The ABCD2 score had predictive value in tissue-positive and tissue-negative events (AUC = 0.68 [95% confidence interval 0.63-0.73] and 0.73 [0.67-0.80], respectively; p sig < 0.0001 for both results, p diff = 0.17). Tissue-positive events with low ABCD2 scores and tissue-negative events with high ABCD2 scores had similar stroke risks, especially after a 90-day follow-up.
  
  
  CONCLUSIONS
  Our findings support the concept of a tissue-based definition of TIA and stroke, at least on prognostic grounds.
authors.affiliation: Stroke Prevention Research Unit, NIHR Biomedical Research Centre, Oxford University Department of Clinical Neurology, Level 6, West Wing, John Radcliffe Hospital, Oxford OX3 9DU, UK. matthew.giles@clneuro.ox.ac.uk
authors.forename: M F
authors.initials: MF
authors.lastname: Giles
authors.forename: G W
authors.initials: GW
authors.lastname: Albers
authors.forename: P
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authors.lastname: Amarenco
authors.forename: E M
authors.initials: EM
authors.lastname: Arsava
authors.forename: A W
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authors.lastname: Asimos
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authors.forename: A S
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authors.lastname: Kim
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authors.lastname: Labreuche
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authors.lastname: Purroy
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mesh_terms: D019540:Area Under Curve; D015331:Cohort Studies; D038524:Diffusion Magnetic Resonance Imaging; D005260:Female; D006801:Humans; D007391:International Cooperation; D002546:Ischemic Attack, Transient / Q000175:diagnosis*; D008297:Male; D011237:Predictive Value of Tests; D012307:Risk Factors; D012720:Severity of Illness Index; D018709:Statistics, Nonparametric; D020521:Stroke / Q000175:diagnosis; D013997:Time Factors; D014057:Tomography, X-Ray Computed