Bleeding risk in patients with venous thromboembolic events treated with new oral anticoagulants.

New oral anticoagulants (NOACs) is the preferred treatment in secondary prophylaxis of venous thromboembolic events (VTE). The aim of this study was to investigate possible risk factors associated with major bleeding in VTE-patients treated with NOACs. In this retrospective register-based study we screened the Swedish anticoagulation register Auricula (during 2012.01.01-2017.12.31) to find patients and used other national registers for outcomes. Primary endpoint was major bleeding defined as bleeding leading to hospital care. Multivariate Cox-regression analysis was used to reveal risk factors. 18 219 patients with NOAC due to VTE were included. 85.6% had their first VTE, mean age was 69.4 years and median follow-up time was 183 days. The most common NOAC was rivaroxaban (54.8%), followed by apixaban (42.0%), dabigatran (3.2%) and edoxaban (0.1%). The rate of major bleeding was 6.62 (95% CI 6.19-7.06) per 100 treatment years in all patients and 11.27 (CI 9.96-12.57) in patients above 80 years of age. Statistically independent risk factors associated with major bleeding were age (normalized HR 1.38, CI 1.27-1.50), earlier major bleeding (HR 1.58, Cl 1.09-2.30), COPD (HR 1.28, CI 1.04-1.60) and previous stroke (HR 1.28, Cl 1.03-1.58) or transient ischemic attack (TIA) (HR 1.33, Cl 1.01-1.76). Prior warfarin treatment was protective (HR 0.67, CI 0.58-0.78). This real world cohort shows a high bleeding rate especially among the elderly and in patients with previous major bleeding, COPD and previous stroke or TIA. This should be considered when deciding on treatment duration and NOAC dose in these patients.