Long-term risk of stroke after transient ischaemic attack: A hospital-based validation of the ABCD² rule

Background: The ABCD² clinical prediction rule is a seven point summation of clinical factors independently predictive of stroke risk. The purpose of this cohort study is to validate the ABCD² rule in a Bulgarian hospital up to three years after TIA. Methods. All consecutive admissions to an emergency department with symptoms of a first TIA were included. Baseline data and clinical examinations including the ABCD² scores were documented by neurologists. Discrimination and calibration performance was examined using ABCD² cut-off scores of ≥3, ≥4 and ≥5 points, consistent with the international guidelines. The Hosmer-Lemeshow test was used to examine calibration between the observed and expected outcomes as predicted by ABCD² score within the logistic regression analysis. Results: Eighty-nine patients were enrolled to the study with a mean age of 63 years (+/- 12 years). Fifty-nine percent (n = 53) of the study population was male. Seven strokes (7 · 8%) occurred within the first year and six further strokes within the three-year follow-up period. There was no incident of stroke within the first 90 days after TIA. The rule demonstrated good predictive (OR = 1·58, 95% CI 1·09-2·29) and discriminative performance (AUC_ROC = 0·72, 95% CI 0 · 58-0 · 86), as well as a moderate calibration performance at three years. Conclusion: This validation of the ABCD² rule in a Bulgarian hospital demonstrates that the rule has good predictive and discriminative performance at three years. The ABCD² is quick to administer and may serve as a useful tool to assist clinicians in the long-term management of individuals with TIA.