A Multicenter Evaluation of the ABCD2 Score's Accuracy for Predicting Early Ischemic Stroke in Admitted Patients With Transient Ischemic Attack

Presented at the ACEP Research Forum, October 2008, Chicago, IL.

Received 2 October 2008; received in revised form 24 March 2009; accepted 1 May 2009. published online 26 June 2009.

Study objective

We evaluate, in admitted patients with transient ischemic attack, the accuracy of the ABCD2 (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 (≤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 ABCD2 score in 613 patients (37%); however, our imputed analysis indicated this did not significantly alter results. The discriminatory power of the ABCD2 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 ABCD2 score (≤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 ABCD2 score may be to identify patients at low risk for an early disabling ischemic stroke. Further study of the ability to determine an ABCD2 score in all patients is needed, along with validation in a large, consecutive population of patients with transient ischemic attack.

a Department of Emergency Medicine, Carolinas Medical Center, Charlotte, NC

b Neurosciences and Spine Institute, Carolinas Medical Center, Charlotte, NC

c Department of Emergency Medicine, Carolinas Medical Center, Charlotte, NC

d Department of Epidemiology, University of North Carolina School of Public Health, Chapel Hill, NC

e Department of Biostatistics, University of North Carolina, Chapel Hill, NC

f Department of Neurology, Wake Forest University School of Medicine, Winston-Salem, NC

g Department of Neurology, University of North Carolina at Chapel Hill, Chapel Hill, NC

Address for correspondence: Andrew W. Asimos, MD, PO Box 32861, Charlotte, NC 28232-2861

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Supervising editor: Robert Silbergleit, MD

Author contributions: AWA conceived the study, obtained research funding, and recruited participating centers. AWA, AMJ, WDR, CHT, and AF designed the trial. AWA, WDR, MFP, and CVM supervised the conduct of the trial and data collection. AWA, MFP, SS, CHT, and AF performed some data collection. MFP and CVM managed the data, including quality control. AMJ, WDR, KMR, and DC provided statistical advice on study design and supervised data analysis. AMJ performed all data analyses. AWA drafted the article, and AMJ, WDR, and KMR contributed substantially to its revision. AWA takes responsibility for the paper as a whole.

Funding and support: By Annals policy, all authors are required to disclose any and all commercial, financial, and other relationships in any way related to the subject of this article that might create any potential conflict of interest. See the Manuscript Submission Agreement in this issue for examples of specific conflicts covered by this statement. This work was supported by the Emergency Medicine Foundation and the Foundation for Education and Research in Neurological Emergencies, along with a grant from Boehringer Ingelheim Pharmaceuticals, Inc.

Publication date: Available online June 24, 2009.

Reprints not available from the authors.

PII: S0196-0644(09)00485-5

doi:10.1016/j.annemergmed.2009.05.002

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