(255) Risk of Severe Uterine Bleeding of Oral Anticoagulants use in Postmenopausal Women Aged 55 Years or Older: An Application of the U.S. Sentinel Routine Querying Tools to the Taiwan Sentinel Data Model

Publication Number: 1245

Background: Evidence regarding the risk of severe uterine bleeding (SUB) of oral anticoagulants use among postmenopausal women is scarce. Whether oral anticoagulants use would increase severe uterine bleeding risk remains unanswered.

Objectives: To evaluate the risk of SUB among oral anticoagulants (warfarin and non-vitamin K antagonists [NOACs]) use in postmenopausal women aged 55 years or older by applying the U.S. Sentinel Routine Querying Tools to the Taiwan Sentinel Data Model (TSDM).

Methods: This was a retrospective cohort study with a new-user design. We adapted the design proposed by the Sentinel System and applied the U.S. Sentinel Routine Query Tools to the TSDM to conduct this study. We converted the Taiwan’s National Health Insurance Research Database (NHIRD) to the TSDM based on the U.S. Sentinel Common Data Model (SCDM) version 6.0.2. Women aged 55 years or older who were newly prescribed warfarin, NOACs, and statin between 2015 and 2019 were included. Statin users served as a common comparison group, and two drug comparison cohorts were evaluated: 1) warfarin (exposure) versus statins (reference), and 2) NOAC (exposure) versus statin (reference). We performed 1:5 propensity score (PS)-matching to balance covariates between treatment groups. Outcome measure was the occurrence of SUB, gastrointestinal (GI) bleeding, and intracranial bleeding (ICH). Cox-proportional hazard models were performed to estimate the risk of bleeding event between treatment groups.

Results: After 1:5 PS matching, there were 15,661 warfarin users matched with 78,305 statin users, and 23,242 NOACs users matched with 116,210 statin users. Compared to statins, warfarin was associated with significantly higher risks of SUB (Hazard ratio [HR]: 2.56; 95% CI: 1.62-4.04), GI bleeding (HR: 2.50; 95% CI: 2.08-3.01), and ICH (HR: 3.77; 95% CI: 2.66-5.34). NOACs were also associated with higher risks of SUB (HR: 1.81; 95% CI: 1.25-2.62) and GI bleeding (HR: 1.60; 95% CI: 1.30-1.97) than statins. However, the risk of ICH was similar between NOAC and statins.

Conclusions: Warfarin and NOAC were both associated with an increased risk of SUB compared to statins. Compared to statin users, the relative risk of SUB seemed to be higher in warfarin users than that in the NOAC users. Postmenopausal women who used oral anticoagulants should be aware of the increased risk of SUB.