Novel bleeding risk score for patients with atrial fibrillation on oral anticoagulants, including direct oral anticoagulants

Objective Balancing bleeding risk and stroke risk in patients with atrial fibrillation (AF) is a common challenge. Though several bleeding risk scores exist, most have not included patients on direct oral anticoagulants (DOACs). We aimed at developing a novel bleeding risk score for patients with AF on oral anticoagulants (OAC) including both vitamin K antagonists (VKA) and DOACs. Methods We included patients with AF on OACs from a prospective multicenter cohort study in Switzerland (SWISS-AF). The outcome was time to first bleeding. Bleeding events were defined as major or clinically relevant non-major bleeding. We used backward elimination to identify bleeding risk variables. We derived the score using a point score system based on the beta-coefficients from the multivariable model. We used the Brier score for model calibration (<0.25 indicating good calibration), and Harrel's c-statistics for model discrimination. Results We included 2147 patients with AF on OAC (72.5% male, mean age 73.4 +/- 8.2 years), of whom 1209 (56.3%) took DOACs. After a follow-up of 4.4 years, a total of 255 (11.9%) bleeding events occurred. After backward elimination, age > 75 years, history of cancer, prior major hemorrhage, and arterial hypertension remained in the final prediction model. The Brier score was 0.23 (95% confidence interval [CI] 0.19-0.27), the c-statistic at 12 months was 0.71 (95% CI 0.63-0.80). Conclusion In this prospective cohort study of AF patients and predominantly DOAC users, we successfully derived a bleeding risk prediction model with good calibration and discrimination.