External Validation and Comparison of Published Stroke Risk Scores in a Chinese Cohort of Patients with Atrial...

Accurate prediction of ischemic stroke or systemic embolism is central to atrial fibrillation (AF) management, yet the transportability of available risk scores to Chinese populations remains uncertain.

Externally validate and compare published stroke risk scores in Chinese patients with non-valvular AF.

We systematically retrieved and externally validated 17 published models in a retrospective cohort of 1,283 adults hospitalized with non-valvular AF at a Chinese tertiary-care center. Discrimination was evaluated using the 4-year Uno C-index and time-dependent areas under the curve (AUC). Models providing absolute risks also underwent calibration, Brier score, and reclassification analyses. Sensitivity analyses accounted for death as a competing event and separately evaluated patients not receiving OAC at baseline.

During 4 years of follow-up, 103 primary outcomes occurred, corresponding to 2.85 events per 100 person-years. Across models, 4-year Uno C-indices ranged from 0.572 to 0.767, compared with 0.690 for CHA₂DS₂-VASc. GARFIELD-AF 2017, GARFIELD-AF 2021, and ATRIA had higher Uno C-indices than CHA₂DS₂-VASc. However, no model had significantly higher time-dependent AUC at any time point. For 1-year calibration, CHA₂DS₂-VASc had predicted and observed risks of 3.39% and 3.54%, respectively, with an observed-to-expected ratio of 1.04, whereas several other models underestimated risk. Brier scores and reclassification measures showed no consistent advantage Competing-risk analyses lowered cumulative incidence without changing comparative patterns. Among patients not receiving OAC at baseline, no model outperformed CHA₂DS₂-VASc.

Candidate models did not consistently outperform CHA₂DS₂-VASc in this external validation; CHA₂DS₂-VASc remains practical, while other models may require population-specific validation and recalibration.