High ABCD2-score after transient ischemic attack is associated with a two-fold higher stroke-rate during long-term follow-up

Background The ABCD2-score is a validated risk score used to estimate the short-term risk of stroke after transient ischemic attack (TIA). However, "real-world" contemporary data on the long-term risk of stroke after TIA according to ABCD2-score are needed in order to guide preventive strategies. Purpose To determine the long-term risk of stroke after TIA according to modified ABCD2-score (high-risk (≥4 points) versus low-risk (<4 points)). Methods Patients aged ≥18 years with first-time TIA were included from the Danish Stroke Registry (2014-2020). The study population was stratified in high-risk (≥4 points) and low-risk (<4 points) ABCD2-score group. We utilized a modified ABCD2-score consisting of the following parameters: age ≥60 years, hypertension, clinical features, and diabetes. The 3-year risk of ischemic stroke and all-cause mortality was compared between the high-risk and low-risk group using the Aalen-Johansen and Kaplan-Meier estimator. A cox regression model was also conducted. Results In total, 21,433 patients with first-time TIA were included; 1,281 (6.0%) in the high-risk and 20,152 (94.0%) in the low-risk group. Patients in the high-risk group were older (77.5 years [interquartile range [IQR] 70.8-84.1] versus 70.3 years [IQR 60.1-78.2]), more often females (52.2% versus 46.6%) (p <0.001), more comorbid and received more medication compared with the low-risk group at baseline. The 3-year cumulative incidence of stroke 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, and the unadjusted hazard ratio (HR) was 1.6 (95% CI 1.2 – 2.0) (Figure 1). The cumulative incidence of all-cause mortality within three-years after TIA 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. The unadjusted HR was 3.2 (95% CI 2.8 – 3.6). Conclusions Patients with high-risk ABCD2-scores had an almost two-fold higher associated long-term stroke-rate compared to those with low-risk scores. Trials focusing on preventive measures, including evidence-based antithrombotic strategies, especially for the high-risk group are warranted.