Less abnormal uterine bleeding with dabigatran than warfarin in women treated for acute venous thromboembolism

Essentials Factor Xa inhibitors cause more abnormal menstrual bleeding (AUB) than vitamin‐K antagonists (VKA). We analyzed data of AUB in women, evaluating dabigatran versus VKA. We observed a 41% lower risk of AUB in women on dabigatran compared to those on VKA. Our findings of lower AUB risk on dabigatran should be corroborated in future studies. Summary Introduction Although direct oral anticoagulants (DOACs) are associated with a better safety profile than warfarin in patients with acute venous thromboembolism (VTE), direct factor Xa inhibitors involve a higher risk of abnormal uterine bleeding (AUB). We aimed to determine the risk of AUB during anticoagulation with dabigatran compared with warfarin. Methods Post‐hoc analysis of the pooled RE‐COVER studies and the RE‐MEDY trial. Incidences of AUB, based on a defined preferred terms search for adverse events, in female patients aged 18–50 years treated with dabigatran, were compared with those in women treated with warfarin. Results Of the 2964 women included in the above‐mentioned trials, 1280 women were in the relevant age category (18–50 years) and included in the current analysis. A total of 643 patients were randomized to treatment with dabigatran and 637 to treatment with warfarin. The overall rate of AUB was 8.1%, 5.9% for the women treated with dabigatran and 9.6% in those treated with warfarin, for an odds ratio for dabigatran‐treated patients of 0.59 (95% confidence interval [CI], 0.39–0.90; P = 0.015). In the dabigatran‐treated patients, three (0.5%) suffered major bleeding (MB) vs. five (0.8%) in the warfarin‐treated patients (HR, 0.65; 95% CI, 0.15–2.72). MB or non‐major relevant bleeding occurred in 30 (4.7%) patients randomized to receive dabigatran and 57 (8.9%) randomized to receive warfarin (HR, 0.53; 95% CI, 0.34–0.83). None of the bleeding events was fatal. Conclusion Dabigatran treatment was associated with a significantly (41%) lower risk of AUB than warfarin. Future studies in daily practice are needed to corroborate these findings.