FACTORS ASSOCIATED WITH INAPPROPRIATE APIXABAN DOSING PERSISTENCE IN NONVALVULAR ATRIAL FIBRILLATION PATIENTS AT A UNIVERSITY TEACHING HOSPITAL IN RIYADH, SAUDI ARABIA

Direct oral anticoagulants (DOACs), including apixaban, have addressed limitations associated with warfarin use for anticoagulation in patients with nonvalvular atrial fibrillation (NVAF). While data suggest that apixaban is safe, its safety depends on appropriate dosing. This single-centre retrospective cohort study aimed to evaluate patient-related factors associated with the persistence of inappropriate apixaban prescribing and to describe bleeding events during follow-up. The records from King Khalid University Hospital (KKUH), Riyadh, Saudi Arabia, were reviewed between January 2020 and December 2022. Among 367 patient records examined, 227 (61.85%) received the appropriate apixaban dose, while 140 (38.15%) were inappropriately dosed, with the vast majority being underdosed (132 patients, 94.3%). Inappropriate do sing persisted in 108 patients (29.4%) during follow-up. Female sex, age (≥ 75 years), overweight/obesity and antiplatelet use were identified as key contributors to persistent inappropriate dosing, though none reached statistical significance. Although th ese findings were not statistically significant, they have important clinical implications, as inappropriate dosing may compromise anticoagulation efficacy. Seventeen patients (4.6%) experienced bleeding events, with most occurring during periods of underd osing or appropriate dosing. These results underscore the importance of continued clinician education and decision support tools to optimise anticoagulant therapy and improve outcomes in patients with NVAF.