A multicenter evaluation of the ABCD2 score's accuracy for predicting early ischemic stroke in admitted patients with transient ischemic attack

Study objective: We evaluate, in admitted patients with transient ischemic attack, the accuracy of the ABCD(2) (age [A], blood pressure [B], clinical features [weakness/speech disturbance] [C], transient ischemic attack duration [D], and diabetes history [D]) score in predicting ischemic stroke within 7 days.

Methods: At 16 North Carolina hospitals, we enrolled a prospective, nonconsecutive sample of admitted patients with transient ischemic attack and with no stroke history, presenting within 24 hours of transient ischemic attack symptom onset. We conducted a medical record review to determine ischemic stroke outcomes within 7 days. According to a modified Rankin Scale Score, strokes were classified as disabling (>2) or nondisabling (< or =2).

Results: During a 35-month period, we enrolled 1,667 patients, of whom 373 (23%) received a diagnosis of an ischemic stroke within 7 days. Eighteen percent (69/373) of all strokes were disabling. We were unable to calculate an ABCD(2) score in 613 patients (37%); however, our imputed analysis indicated this did not significantly alter results. The discriminatory power of the ABCD(2) score was modest for ischemic stroke in 7 days (c statistic 0.59), and fair for disabling ischemic stroke within 7 days (c statistic 0.71). Patients characterized as low risk according to ABCD(2) score (< or =3) were at low risk for experiencing a disabling stroke within 7 days, with a negative likelihood ratio of 0.16 (95% confidence interval [CI] 0.04 to 0.64) with missing values excluded and 0.34 (95% CI 0.15 to 0.76) when missing values were imputed.

Conclusion: Our analysis suggests the best application of the ABCD(2) score may be to identify patients at low risk for an early disabling ischemic stroke. Further study of the ability to determine an ABCD(2) score in all patients is needed, along with validation in a large, consecutive population of patients with transient ischemic attack.