SUNG-CHUN TANGSHIN-YI LINCHIH-HAO CHENYEN BIN LIUHo, Li-TingLi-TingHoKuo, Ching-HuaChing-HuaKuoPeng, Yu-FongYu-FongPengJIANN-SHING JENGCHIH-FEN HUANG2025-12-152025-12-152025https://scholars.lib.ntu.edu.tw/handle/123456789/734649This study investigated real-world edoxaban concentrations across different dosing regimens, with a specific focus on patients who met the inclusion criteria of low-dose edoxaban for the Elder Care Atrial Fibrillation (ELDERCARE-AF) trial. Patients with atrial fibrillation receiving edoxaban were enrolled to measure trough concentrations. The levels were compared with the expected therapeutic range (12-43 ng/mL) to define low or high concentrations. Data on ischemic stroke and systemic thromboembolism (SSE), and major bleeding, were collected prospectively. In total, 402 patients (77.2 ± 10.6 years; 52.2% men) were included. The SSE incidence was 1.22 (0.56-2.31) per 100 person years and was significantly associated with low edoxaban concentration (aHR, 4.13 [1.08-15.82]). Among patients meeting the ELDERCARE-AF criteria (n = 160), the use of the 15-mg regimen (ELDER-15 mg, n = 46) vs. the 30-mg regimen (ELDER-30 mg, n = 114) (aOR, 7.65 [2.92-20.09]), higher creatinine clearance (CrCL) (aOR, 1.05 [1.01-1.08]) and lower CHADS-VA score (aOR, 0.69 [0.51, 0.95]) were significantly associated with low concentrations. In the ELDER-15 mg group, patients with CrCL > 50 mL/min had more than 50% probability of exhibiting low drug concentrations. The incidence of SSE was numerically higher in the ELDER-15 mg group than the ELDER-30 mg group (2.34 [0.06-13.02] vs. 1.55 [0.32-4.52]), while major bleeding rates were similar (4.67 [0.57-16.89] vs. 5.15 [2.47-9.48]). In conclusion, low edoxaban concentrations have been associated with thromboembolic events. Among ELDERCARE-AF-eligible patients, the 15-mg regimen results in underexposure to edoxaban, particularly when the CrCL exceeded 50 mL/min.en[SDGs]SDG3journal article10.1002/cpt.7012941243623