Oral anticoagulant switching in patients with atrial fibrillation: a long-term cohort study using population-level administrative data

INTRODUCTION: Patient characteristics and clinical factors could necessitate switching between oral anticoagulants (OACs) for stroke prevention in atrial fibrillation (AF), a phenomenon whose causes and consequences are understudied. AIM: Our objectives were to describe longitudinal patterns of OAC switching in patients with AF and to identify factors associated with switching. METHOD: A cohort of adult AF patients were identified in Canadian administrative health data from 1996 to 2019. An OAC switch was defined as a change from one OAC to a different OAC with a gap of ≤ 30 days between prescriptions. Switch events were characterized, and factors associated with switches were analyzed using Cox regression. RESULTS: The cohort comprised 30,264 patients. One quarter experienced an OAC switch and 22% of those had ≥ 2 switch events. Vitamin K antagonist (VKA) to direct-acting oral anticoagulant (DOAC) was the most frequent switch type (63%). Switching to a previous OAC occurred commonly (19%-26%). A quarter of patients who switched from warfarin to a DOAC switched back to warfarin. Hospitalizations for AF, acute renal failure, vascular disease, gastrointestinal bleeding, and/or stroke ≤ 90 days before a switch had the highest hazards for VKA to DOAC switch. Hospitalizations for AF, stroke, major bleeding, vascular disease, and/or heart failure (HF) ≤ 90 days before a switch had the highest hazards for DOAC to VKA switch. Hospitalizations for AF, major bleeding, acute renal failure, vascular disease, stroke, and/or HF ≤ 90 days before a switch had the highest hazards for switch between DOACs. CONCLUSION: OAC switching is frequently required in AF patients, with many needing to return to a previously used agent. Switches may reflect an intention to maximize stroke prevention effectiveness and safety, but further research is needed to assess the risks and benefits of OAC switching.