title: The high risk of stroke immediately after transient ischemic attack: a population-based study.
abstract: BACKGROUND
  The risk of stroke is elevated in the first 48 hours after TIA. Previous prognostic models suggest that diabetes mellitus, age, and clinical symptomatology predict stroke. The authors evaluated the magnitude of risk of stroke and predictors of stroke after TIA in an entire population over time.
  
  
  METHODS
  Administrative data from four different databases were used to define TIA and stroke for the entire province of Alberta for the fiscal year (April 1999-March 2000). The age-adjusted incidence of TIA was estimated using direct standardization to the 1996 Canadian population. The risk of stroke after a diagnosis of TIA in an Alberta emergency room was defined using a Kaplan-Meier survival function. Cox proportional hazards modeling was used to develop adjusted risk estimates. Risk assessment began 24 hours after presentation and therefore the risk of stroke in the first few hours after TIA is not captured by our approach.
  
  
  RESULTS
  TIA was reported among 2,285 patients for an emergency room diagnosed, age-adjusted incidence of 68.2 per 100,000 population (95% CI 65.3 to 70.9). The risk of stroke after TIA was 9.5% (95% CI 8.3 to 10.7) at 90 days and 14.5% (95% CI 12.8 to 16.2) at 1 year. The risk of combined stroke, myocardial infarction, or death was 21.8% (95% CI 20.0 to 23.6) at 1 year. Hypertension, diabetes mellitus, and older age predicted stroke at 1 year but not earlier.
  
  
  CONCLUSIONS
  Although stroke is common after TIA, the early risk is not predicted by clinical and demographic factors. Validated models to identify which patients require urgent intervention are needed.
authors.affiliation: Calgary Stroke Program, Department of Clinical Neurosciences, University of Calgary, Canada. michael.hill@calgaryhealthregion.ca
authors.forename: M D
authors.initials: MD
authors.lastname: Hill
authors.forename: N
authors.initials: N
authors.lastname: Yiannakoulias
authors.forename: T
authors.initials: T
authors.lastname: Jeerakathil
authors.forename: J V
authors.initials: JV
authors.lastname: Tu
authors.forename: L W
authors.initials: LW
authors.lastname: Svenson
authors.forename: D P
authors.initials: DP
authors.lastname: Schopflocher
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D000416:Alberta / Q000453:epidemiology; D003430:Cross-Sectional Studies; D016208:Databases, Factual; D018450:Disease Progression; D018572:Disease-Free Survival; D004636:Emergency Service, Hospital / Q000706:statistics & numerical data; D005260:Female; D006801:Humans; D002546:Ischemic Attack, Transient / Q000453:epidemiology*; D015993:Life Tables; D008297:Male; D008875:Middle Aged; D009203:Myocardial Infarction / Q000453:epidemiology; D016016:Proportional Hazards Models; D018570:Risk Assessment; D012307:Risk Factors; D012959:Socioeconomic Factors; D020521:Stroke / Q000453:epidemiology*; D016019:Survival Analysis; D013997:Time Factors