Article Citation: Johnston SC, Rothwell PM, Nguyen-Huynh MN, Giles MF, et al. Validation and refinement of scores to predict very early stroke risk after transient ischaemic attack. Lancet. 2007;369(9558):283-92.

What we already know about the topic: A patient with a TIA is at increased risk of stroke but it’s hard to predict how likely an individual patient with TIA will have a stroke over the next 48 hours.  

ABCD score: 7 day risk of stroke following a TIA

California score: 90 day risk of stroke following a TIA

Why this study is important: it allows us to risk stratify our patients with TIA and decide whether they can receive safe outpatient follow up or they should be admitted to the hospital for further intervention/management/diagnostics.

Brief overview of the study: The California and ABCD scores were validated in four independent groups of patients diagnosed with TIA in EDs and clinics in USA and UK (n = 2893).  The two groups that were used to derive the original scores (n = 1916) were used to derive a new unified score based on logistic regression.  The c statistic was used to measure predictive ability and all combinations of factors from ABCD and California scores were tested for their c statistic and the combination with the highest statistic for 2-day risk of stroke was selected and validated.  The two derivation groups and four validations groups included 4809 patients with TIA.

ABCD2: age >=60 (1), BP >= 140/90 (1), clinical features of TIA (unilateral weakness 2; speech disturbance without weakness 1), duration of symptoms (10-59 mins 1; >= 60 mins 2), DM (1)

Two day stroke risk after a TIA based on ABCD2 score: Low risk (0-3): 1%, moderate risk (4-5): 4.1%, high risk (6-7): 8.1%

Stroke risk at 7 and 90 days was also studied and was found to be higher in patients with higher ABCD2 scores.

Limitations: study population included EDs and clinics so maybe not generalizable to our ED population; some data gathered retrospectively in the US cohorts and data was obtained without knowledge of subsequent events so this could underestimate the true predictive value of the score.

Take home points:

  1. ABCD2 score is a risk stratification tool (7 points total) that identifies patients at high risk for stroke after a TIA
  2. Two day stroke risk after a TIA based on ABCD2 score: Low risk (0-3): 1%, moderate risk (4-5): 4.1%, high risk (6-7): 8.1%
  3. Patients with scores >= 4 (moderate and high risk) might require inpatient admission and possible intervention