Efficacy and Safety of Novel Oral Anticoagulants in Elderly Patients with Non-Valvular Atrial Fibrillation: A Retrospective Cohort Study

Adults aged 80 years or older with nonvalvular atrial fibrillation (NVAF) often have competing thromboembolic and bleeding risks, renal impairment, frailty, and dose-selection challenges. This single-center retrospective observational cohort included 202 adults aged 80 years or older who received warfarin (n = 56), edoxaban 60 mg once daily (n = 38), edoxaban 30 mg once daily (n = 41), rivaroxaban 15 mg once daily (n = 35), or rivaroxaban 10 mg once daily (n = 32). Six-month embolic events, International Society on Thrombosis and Hemostasis (ISTH) bleeding categories, other adverse reactions, official-label dose concordance, dynamic risk scores, and serial laboratory measurements were evaluated. Exploratory generalized overlap weighting addressed measured treatment-selection differences. Embolic events occurred in 8 patients and ISTH minor bleeding in 21; neither outcome differed significantly among groups (exact p = 0.846 and p = 0.199, respectively). No ISTH major or clinically relevant non-major bleeding occurred. Other adverse reactions differed overall (p = 0.014), but pairwise estimates were imprecise. Of 146 direct oral anticoagulant recipients, 72 (49.3%) received a baseline dose concordant with the prespecified official-label framework, 72 (49.3%) received a lower-than-label dose, and 2 (1.4%) received a higher-than-label dose. Low event counts and marked treatment-selection imbalance prevented conclusions of equivalence, superiority, or greater safety. The findings require confirmation in larger, prospectively defined cohorts with longer follow-up, predefined label-dose criteria, and stronger control of confounding.