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(Stroke. 2009;40:3449.)
© 2009 American Heart Association, Inc.

Original Contributions

Diagnostic Usefulness of the ABCD² Score to Distinguish Transient Ischemic Attack and Minor Ischemic Stroke From Noncerebrovascular Events

The North Dublin TIA Study

Orla C. Sheehan, MB, MRCPI; Aine Merwick, MB, MRCPI; Lisa A. Kelly, MB, MRCPI; Niamh Hannon, MB, MRCPI; Michael Marnane, MB, MRCPI; Lorraine Kyne, MD, MPH, FRCPI; Patricia M.E. McCormack, MD, FRCPI, DCH; Joseph Duggan, MD, FRCPI; Alan Moore, MD, FRCPI; Joan Moroney, MD, MPH, FRCPI; Leslie Daly, MSc, PhD, FFPH; Dawn Harris, BSc; Gillian Horgan, BSc Peter J. Kelly, MD, MS, FRCPI

From The Neurovascular Clinical Science Unit (O.C.S., A.M., L.A.K., N.H., M.M., L.K., J.D., J.M., D.H., G.H., P.J.K.), Mater University Hospital, University College Dublin, Dublin, Ireland; Connolly Hospital (P.M.E.M.), Ireland; Beaumont Hospital (A.M.), Ireland; and the School of Public Health and Population Science (L.D.), University College Dublin, Dublin, Ireland.

Correspondence to Prof Peter Kelly, Neurovascular Clinical Science Unit, Catherine McAuley Research Centre, Mater University Hospital, Dublin 7, Ireland. E-mail ndpss{at}mater.ie

Background and Purpose— Transient ischemic attack (TIA) diagnosis is frequently difficult in clinical practice. Noncerebrovascular symptoms are often misclassified as TIA by nonspecialist physicians. Clinical prediction rules such as ABCD² improve the identification of patients with TIA at high risk of early stroke. We hypothesized that the ABCD² score may partly improve risk stratification due to improved discrimination of true TIA and minor ischemic stroke (MIS) from noncerebrovascular events.

Methods— Consecutive patients with TIA were identified within a prospective population-based cohort study of stroke and TIA. The cohort was expanded by inclusion of patients with MIS and noncerebrovascular events referred to a daily TIA clinic serving the population. Diagnosis was assigned by a trained stroke physician independent of ABCD² score.

Results— Five hundred ninety-four patients were included (292 [49.2%] TIA, 45 [7.6%] MIS, and 257 [43.3%] noncerebrovascular). The mean ABCD² score showed a graded increase across diagnostic groups (MIS mean 4.8 [SD 1.4] versus TIA mean 3.9 [SD 1.5] versus noncerebrovascular mean 2.9 [SD 1.5]; P<0.00001). The ABCD² score discriminated well between noncerebrovascular and cerebrovascular events—TIA (c-statistic 0.68; 95% CI, 0.64 to 0.72), any vascular event (TIA+MIS; c-statistic 0.7; 95% CI, 0.66 to 0.74), and MIS (c-statistic 0.81; 95% CI, 0.75 to 0.87)—from noncerebrovascular events. Of ABCD² items, unilateral weakness (OR, 4.5; 95% CI, 3.1 to 6.6) and speech disturbance (OR, 2.5; 95% CI, 1.6, 4.1) were most likely overrepresented in TIA compared with noncerebrovascular groups.

Conclusion— The ABCD² score had significant diagnostic usefulness for discrimination of true TIA and MIS from noncerebrovascular events, which may contribute to its predictive usefulness.

Key Words: ABCD² score • cerebrovascular disorders • diagnosis • transient ischemic attack