Underdosed Edoxaban and Clinical Outcomes in Patients with Non-valvular Atrial Fibrillation in Real World: A Retrospective Cohort Study

Background Underdosed edoxaban was prevalent in Asian clinical practice, yet its outcomes in patients with non-valvular atrial fibrillation (AF) remain unclear. Methods We conducted a retrospective cohort study at a Chinese tertiary-care hospital to investigate the real-world effectiveness and safety of underdosed edoxaban in patients with AF. According to international dosing criteria, patients were stratified into recommended dose group and under dosed group. After inverse probability of treatment weighting, the effectiveness endpoints (ischemic stroke (IS) or systemic embolism (SE), all-cause mortality) and safety endpoints (major bleeding and clinically relevant non-major [CRNM] bleeding) were evaluated between the two groups. Results Of 616 included non-valvular AF patients, 31.5% received an underdosed edoxaban regimen. The under dosed group showed no significant differences in the risk of IS or SE (HR 0.78, 95%CI 0.18–3.32), major bleeding (HR 0.19, 95%CI 0.01–2.12), or all-cause mortality (HR 0.60, 95%CI 0.28–1.31) compared to the recommended dose group. However, a significant reduction in CRNM bleeding was observed in the under dosed group (HR 0.47, 95%CI 0.23–0.95). Conclusion In this real-world Chinese tertiary-care cohort, underdosed edoxaban was administered to nearly one-third of patients with non-valvular AF. Compared with the recommended dose, this dosing strategy was associated with comparable risks of IS/SE and major bleeding, as well as a potentially lower incidence of CRNM bleeding. These findings should be considered preliminary and warrant validation in larger, multi-center prospective studies.