Oral anticoagulant prescribing and DOAC dosing appropriateness in patients with non-valvular atrial fibrillation: a retrospective study from Vietnam

Background Direct oral anticoagulants (DOACs) are recommended over vitamin K antagonists (VKAs) for stroke prevention in patients with non-valvular atrial fibrillation (NVAF). However, real-world prescribing patterns and dosing appropriateness in low- and middle-income countries remain poorly characterized. This study evaluated patterns of oral anticoagulant use and identified clinical determinants of suboptimal prescribing in a tertiary cardiovascular center in Vietnam. Methods We conducted a retrospective observational study of 209 patients with NVAF who received oral anticoagulation at a tertiary cardiovascular center between 2023 and 2024. Data were extracted from electronic medical records, including demographics, comorbidities, renal function, bleeding history, and prescribed anticoagulants. Multivariable logistic regression was used to identify factors associated with anticoagulant selection, defined as DOAC versus VKA use. DOAC dosing appropriateness was assessed according to the 2021 European Heart Rhythm Association Practical Guide, and predictors of potentially inappropriate dose reduction were evaluated. Results DOACs were prescribed in 77.0% of patients, most commonly rivaroxaban, which accounted for 55.3% of all anticoagulant prescriptions. VKAs were prescribed in 23.0% of patients. Among VKA users, 85.4% had INR values outside the therapeutic range at admission, largely due to subtherapeutic international normalized ratio values. Reduced DOAC doses were prescribed in 88 of 161 DOAC users (54.7%). Among 85 assessable reduced-dose DOAC users, 42 (49.4%) were classified as having potentially inappropriate dose reduction. In the parsimonious multivariable model, age ≥ 75 years was associated with higher odds of DOAC use (odds ratio [OR] 5.08; 95% confidence interval [CI] 1.95–13.23; p = 0.001), whereas female sex (OR 0.43; 95% CI 0.21–0.91; p = 0.027), heart failure (OR 0.23; 95% CI 0.09–0.59; p = 0.002), and prior bleeding (OR 0.20; 95% CI 0.05–0.87; p = 0.031) were associated with lower odds of DOAC use. Conclusion In this single-center retrospective study from Vietnam, oral anticoagulant prescribing in patients with NVAF showed several areas for optimization, including frequent INR values outside the therapeutic range at admission among VKA users and frequent potentially inappropriate DOAC dose reduction. These findings support the need for improved dose optimization, and monitoring strategies, but should be interpreted cautiously give the observational design and inpatients data source.