Abnormal Uterine Bleeding Among Oral Anticoagulant Users

OBJECTIVE: To estimate the real-world incidence of abnormal uterine bleeding after oral anticoagulant initiation with a large national claims database, stratified by agent and age group. METHODS: We conducted a nested matched case-control study using the MarketScan Research Databases (2008-2022). Women 18 years of age or older initiating oral anticoagulants (warfarin, apixaban, rivaroxaban, dabigatran, and edoxaban) for deep venous thrombosis, pulmonary embolism, or atrial fibrillation or flutter were matched 1:5 to anticoagulant nonusers. The primary outcome was abnormal uterine bleeding (AUB) within 1 year. Secondary outcomes included the risk of hospitalizations, emergency department visits, and outpatient encounters related to AUB. All estimates were derived from conditional logistic regression models adjusted for matching factors and baseline clinical covariates. RESULTS: Among 276,911 anticoagulant users and 1,384,555 matched controls, the incidence of AUB was significantly higher in anticoagulant users (6.1% vs 3.0%, adjusted odds ratio [AOR] 1.81, 95% CI, 1.69-1.93). Anticoagulant users had higher odds of AUB-related hospitalization (0.8% vs 0.01%, AOR 62.32, 95% CI, 30.94-125.53), emergency department visits (0.9% vs 0.2%, AOR 5.78, 95% CI, 4.02-8.31), and outpatient encounters (4.6% vs 2.8%, AOR 1.42, 95% CI, 1.32-1.52). Women younger than 50 years of age had a greater relative increase in AUB (19.7% vs 9.2%, AOR 1.96, 95% CI, 1.79-2.14) compared with women 50 years of age or older (3.8% vs 2.0%, AOR 1.63, 95% CI, 1.50-1.78). Among all agents, rivaroxaban was associated with the highest risk of AUB. CONCLUSION: Oral anticoagulant therapy is associated with significantly increased odds of AUB, particularly among younger women. Rivaroxaban conferred the highest AUB risk.