Comparison of Stroke Prediction Accuracy of ABCD2 and ABCD3-I in Patients with Transient Ischemic Attack: A Meta-Analysis

Background: A direct comparison of the stroke prediction utility of the ABCD2 and ABCD3-I scores has not been performed. Thus, we conducted a diagnostic meta-analysis and applied the results to a hypothetical cohort of 1000 patients with transient ischemic attack (TIA) to assess the power of stroke prediction by ABCD2 and ABCD3-I scores. Methods: Medline, PubMed, Embase, and manuscript references were searched to identify studies that directly compared the stroke predictive powers of ABCD2 and ABCD3-I scores. We conducted a diagnostic meta-analysis using bivariate random effects models, and the predictive powers of ABCD2 and ABCD3-I scores were assessed by their summary sensitivity and specificity. Then, we applied the results to a hypothetical cohort of 1000 patients with TIA to calculate the effect per 1000 patients triaged for stroke prevention in a virtual setting. Results: Of the 35 identified studies on ABCD2 and ABCD3-I, 6 studies (7364 participants) directly compared the diagnostic accuracies of ABCD2 and ABCD3-I scores for occurrence of a future stroke. The pooled sensitivities of ABCD2 versus ABCD3-I were 79.9% (62.2%-90.6%) versus 96.1% (90.2%-98.5%) at 7 days (P = .022), and 76.6% (63.8%-85.8%) versus 94.6% (88.9%-97.5%) at 90 days (P = .001). The pooled specificities of ABCD2 versus ABCD3-I were 29.2% (18.2%-43.3%) versus 17.7% (8.5%-33.3%) at 7 days (P = .214), and 40.3% (25.0%-57.7%) versus 20.2% (12.6%-30.6%) at 90 days (P = .032). Conclusions: ABCD3-I scores had a better sensitivity but poorer specificity than ABCD2 scores. However, in community-based referring settings, it is more suitable to use ABCD2 at initial triage and deciding on urgency of specialist assessment. The prognostic utility of each of the components of the scores should be carefully considered rather than dichotomized scores during clinical triage.