2020 Volume 50 Issue 5 Pages 187-192
Background: Clinical trials have shown efficacy and safety of direct oral anticoagulants (DOAC) comparable with that of warfarin in preventing stroke in patients with non-valvular atrial fibrillation (AF). However, postmarketing surveillance showed that numerous patients received “off-label”under-dosing of DOAC.
Methods: Between 2012 and 2015, consecutive AF patients newly initiated on rivaroxaban with preserved renal function were evaluated and prospectively followed until death or last follow-up. Patients were divided into two groups; taking rivaroxaban 15 mg (standard dose) and 10 mg (“off-label”under-dose). Primar y outcome was cardiovascular events (embolic events or cardiovascular death) and secondar y outcome was hemorrhage. Cox proportional hazards modeling was used to assess independent risk factors for events.
Results: Of 300 non-valvular AF patients (68 ± 10 years old, 22 ％ “off-label”under-dose), 13 (4.3％) had cardiovascular events and 22 (7％) had hemorrhagic events during mean follow-up of 13 ± 11 months. In the multivariable Cox proportional hazards model, “off-label”under-dosing of rivaroxaban carried significant independent risk of cardiovascular events but not hemorrhagic events.
Conclusion: In nonvalvular AF with preserved renal function, “off-label”under-dosing of rivaroxaban carries increased risk of cardiovascular events, but do not prevent hemorrhagic events.
