Incident Stroke After First-Time TIA According to ABCD² Score: A Nationwide Cohort Study

Transient ischemic attack (TIA) is associated with a higher short-term incidence of stroke. However, long-term data on this association are lacking. Therefore, this study aimed to determine the long-term incidence of ischemic stroke after TIA according to ABCD² score and to identify factors associated with stroke after TIA.

All Danish patients ≥18 years with first-time TIA were included from the Danish Stroke Registry (2014-2020). The study population was stratified into a high-risk (≥4 points) and low-risk (<4 points) group according to the modified ABCD² score (age ≥60 years, hypertension, clinical features, and diabetes). The 3-year cumulative incidence of stroke and all-cause mortality was assessed using the Aalen-Johansen and Kaplan-Meier estimators, respectively. Factors associated with 3-year stroke rate were identified using multivariable Cox regression models.

In total, 21,433 patients with first-time TIA were included: 1,280 (6.0%) in the high-risk group and 20,153 (94.0%) in the low-risk group. Patients with high-risk ABCD² scores were older (median 77.5 [P25-P75 70.8-84.1] vs 70.3 [P25-P75 60.1-78.2]), more often female (53.1%), had more comorbidities (e.g., ischemic heart disease, heart failure, and atrial fibrillation), and received more medication (e.g., any antiplatelet therapy or oral anticoagulants and cholesterol-lowering drugs) at baseline. The 3-year cumulative incidence of stroke after TIA was 6.0% (95% CI 4.6-7.5) in the high-risk group and 4.2% (95% CI 3.9-4.5) in the low-risk group (p = 0.004) with an unadjusted hazard ratio (HR) 1.56 (95% CI 1.21-2.00). Factors associated with 3-year stroke rate included age ≥60 years (HR 2.21, 95% CI 1.76-2.78), current smoking (HR 1.37, 95% CI 1.13-1.65), unilateral weakness (HR 1.25, 95% CI 1.04-1.51), peripheral artery disease (HR 1.53, 95% CI 1.09-2.14), and chronic kidney disease (HR 1.39, 95% CI 1.01-1.90). The 3-year cumulative incidence of all-cause mortality was 28.9% (95% CI 26.1-31.7) in the high-risk group and 10.3% (95% CI 9.9-10.8) in the low-risk group.

Patients with high-risk ABCD² score had an almost 60% higher associated long-term rate of ischemic stroke compared with those with low-risk ABCD² score. Future trials focusing on preventive strategies, including evidence-based antithrombotic strategies, especially for the high-risk group are warranted.