(182) Oral anticoagulant prescription trends and adherence among patients with atrial fibrillation and mitral stenosis in Hong Kong

Background: Warfarin is the only oral anticoagulant (OAC) recommended by international guidelines for the management of atrial fibrillation (AF) patients with moderate-severe mitral stenosis (MS). However, there is growing clinical interest in the use of direct oral anticoagulant (DOAC) due to superior safety and comparable efficacy over warfarin among patients with non-valvular AF. Evidence on OAC prescription trends among patients with AF-MS in real-world settings is limited.

Objectives: To describe the OAC prescription trends and adherence among patients with AF-MS in Hong Kong.

Methods: This is a retrospective cohort study using a territory-wide clinical database in Hong Kong. Patients with AF-MS who were prescribed DOACs or warfarin between 1 January 2010 and 31 December 2023 were identified. We analysed the trends of OAC usage and switching. A logistic regression model was used to identify factors associated with switching from warfarin to DOACs.

Results: 2,074 AF-MS patients were identified from 1 January 2010 to 31 December 2023, including 1,892 (91.22%) OAC users. Among patients with AF-MS, DOACs were first used in 2011, and their proportion increased from 1.14% in 2011 to 7.28% in 2023. Specifically, the proportion of dabigatran increased from 1.14% in 2011 to 1.88% in 2023, rivaroxaban increased from 0.19% in 2012 to 0.58% in 2023, apixaban increased from 0.13% in 2014 to 4.39% in 2023, and edoxaban increased from 0.08% in 2017 to 0.68% in 2023. Among all OAC users, 87.10% exclusively used warfarin, 3.38% exclusively used DOACs, and 2.11% of users switched from DOACs to warfarin, with the majority (52.50%) switching within 6 months. Additionally, 7.40% switched from warfarin to DOACs, with half of them (52.86%) switching after 2 years. Factors positively associated with switching from warfarin to DOACs included being ≥75 years old and experiencing major bleeding during the study period.

Conclusions: In real-world settings, despite warfarin remaining the only recommended OAC for patients with AF-MS, there was still off-label use of DOACs. Warfarin users may switch to DOACs due to older age and bleeding events. Determinants of OAC adherence, as well as the safety and effectiveness of DOACs among patients with AF-MS, need to be further explored.