title: Validation and refinement of scores to predict very early stroke risk after transient ischaemic attack.
abstract: BACKGROUND
  We aimed to validate two similar existing prognostic scores for early risk of stroke after transient ischaemic attack (TIA) and to derive and validate a unified score optimised for prediction of 2-day stroke risk to inform emergency management.
  
  
  METHODS
  The California and ABCD scores were validated in four independent groups of patients (n=2893) diagnosed with TIA in emergency departments and clinics in defined populations in the USA and UK. Prognostic value was quantified with c statistics. The two groups used to derive the original scores (n=1916) were used to derive a new unified score based on logistic regression.
  
  
  RESULTS
  The two existing scores predicted the risk of stroke similarly in each of the four validation cohorts, for stroke risks at 2 days, 7 days, and 90 days (c statistics 0.60-0.81). In both derivation groups, c statistics were improved for a unified score based on five factors (age >or=60 years [1 point]; blood pressure >or=140/90 mm Hg [1]; clinical features: unilateral weakness [2], speech impairment without weakness [1]; duration >or=60 min [2] or 10-59 min [1]; and diabetes [1]). This score, ABCD(2), validated well (c statistics 0.62-0.83); overall, 1012 (21%) of patients were classified as high risk (score 6-7, 8.1% 2-day risk), 2169 (45%) as moderate risk (score 4-5, 4.1%), and 1628 (34%) as low risk (score 0-3, 1.0%).
  
  
  CONCLUSIONS
  Existing prognostic scores for stroke risk after TIA validate well on multiple independent cohorts, but the unified ABCD(2) score is likely to be most predictive. Patients at high risk need immediate evaluation to optimise stroke prevention.
authors.affiliation: Stroke Service, Department of Neurology, University of California, San Francisco, CA 94143-0114, USA. clay.johnston@ucsfmedctr.org
authors.forename: S Claiborne
authors.initials: SC
authors.lastname: Johnston
authors.forename: Peter M
authors.initials: PM
authors.lastname: Rothwell
authors.forename: Mai N
authors.initials: MN
authors.lastname: Nguyen-Huynh
authors.forename: Matthew F
authors.initials: MF
authors.lastname: Giles
authors.forename: Jacob S
authors.initials: JS
authors.lastname: Elkins
authors.forename: Allan L
authors.initials: AL
authors.lastname: Bernstein
authors.forename: Stephen
authors.initials: S
authors.lastname: Sidney
mesh_terms: D002140:California; D005260:Female; D006801:Humans; D002546:Ischemic Attack, Transient / Q000145:classification / Q000150:complications* / Q000453:epidemiology; D016015:Logistic Models; D008297:Male; D008875:Middle Aged; D011379:Prognosis; D012307:Risk Factors; D020521:Stroke / Q000175:diagnosis / Q000209:etiology*; D013997:Time Factors; D006113:United Kingdom / Q000453:epidemiology; D014481:United States / Q000453:epidemiology