Appropriateness of direct oral anticoagulant dosing in patients with atrial fibrillation at a tertiary care hospital in Thailand

Background: Appropriate dosing of direct oral anticoagulants (DOACs) has been associated with clinical efficacy and safety. Several studies have shown that DOAC dosing are often inconsistent with guideline recommendations. Little is known about this issue in Thailand. This study aimed to evaluate the appropriateness of DOAC dosing in Thai hospitalized patients with atrial fibrillation (AF). Method: This was a retrospective descriptive study conducted on hospitalized patients at Rajavithi Hospital, a tertiary care hospital in Thailand. Inpatients diagnosed with AF and treated with DOACs between February 2021 and February 2023 were enrolled in the study. The appropriate dosing of DOACs was assessed according to the recommendation of the 2021 European Heart Rhythm Association Practical Guide on the Use of Non-Vitamin K Antagonist Oral Anticoagulants in Patients with Atrial Fibrillation (EHRA). Descriptive statistics were used to analyze the data; median (interquartile range) for continuous variables, and numbers and percentages for categorical variables. Results: A total of 120 patients with AF were evaluated for dosing. The patients received rivaroxaban in 47 cases (39.2 %), apixaban in 32 cases (26.7 %), edoxaban in 31 cases (25.8 %), and dabigatran in 10 cases (8.3 %). Most of the patients were elderly, with a median age of 77.5 (68-84) years. Females were predominant (57.5 %). Our findings indicate that the prevalence of appropriate dosing of DOACs was 63.3 %. However, approximately onethird of patients received inappropriate dosing, with 24 (20.0 %) being overdosed, and 20 (16.7 %) being underdosed. The highest overdosing and underdosing rates were seen in dabigatran (90.0 %) and apixaban (21.9 %), respectively. Conclusion: Inappropriate dosing of DOACs according to the 2021 EHRA recommendations was high in 36.7 %, with overdosing mostly occurring in 20.0 %. The high number of inappropriate dosing highlights the need for implementation of optimal strategies to select the appropriate dose of DOACs in Thai hospitalized patients with AF.