ABCD 2 Score and 90-Day Stroke Risk After Transient Neurological Events by Diffusion-Weighted Imaging Positivity: An Analysis of Pooled Data From 3 Studies

BACKGROUND: The ABCD 2 score is widely used to stratify stroke risk after transient neurological events. We aimed to evaluate the association between the ABCD 2 score and the risk of subsequent ischemic stroke among patients with diffusion-weighted imaging (DWI)–positive (DWI+) or DWI−negative (DWI−) findings for the index event. METHODS: We pooled individual participant data from 3 multicenter cohorts including patients presenting with transient or minor neurological events. Patients presenting with transient neurological symptoms, a normal neurological examination, and available DWI for the index event were included. Associations between the ABCD 2 score and 90-day ischemic stroke risk were analyzed separately in the DWI+ and DWI− groups using logistic regression models adjusted for sex, atrial fibrillation, and study source. RESULTS: Among 2014 patients (1143 [56.8%] men; median age 67 years), the median ABCD 2 score was 4 (interquartile range, 3–5), and 504 (25.0%) were DWI+. Ischemic stroke occurred within 90 days in 20 patients (4.0%) in the DWI+ group and 33 (2.2%) in the DWI− group. The ABCD 2 score was associated with stroke risk in the DWI− group (per 1-point increase, odds ratio, 1.36 [95% CI, 1.04–1.79]), but this relationship was not significant in the DWI+ group (per 1-point increase, odds ratio, 1.08 [95% CI, 0.76–1.53]). When stratified ABCD 2 score into 0 to 3, 4 to 5, and 6 to 7, the predicted 90-day stroke risks were 3.2%, 3.9%, and 4.5% in the DWI+ group (per 1-category increase, odds ratio, 1.23 [95% CI, 0.63–2.40]) and 1.0%, 2.3%, and 4.1% in the DWI− group (per 1-category increase, odds ratio, 1.88 [95% CI, 1.11–3.20]), respectively. CONCLUSIONS: The ABCD 2 score was associated with 90-day stroke risk among patients with DWI− findings. Patients with both a low ABCD 2 score and DWI− findings had a particularly low risk of subsequent stroke, which may inform risk stratification and clinical decision-making after transient neurological events.