Assessment and predictors of inappropriate dose of direct oral anticoagulants

Direct-Acting Oral Anticoagulants (DOACs) have revolutionized the management of Atrial Fibrillation (AF) and Venous Thromboembolism (VTE). However, recent audits reveal a significant burden of inappropriate dosages in the prescribing of direct-acting oral anticoagulants. Our aim is to identify the prevalence and predictors of such inappropriate dosing in our patients. This retrospective study was conducted from June 2016 to January 2018. Patients who received dabigatran, rivaroxaban, or apixaban for treatment of venous thromboembolism or atrial fibrillation were included. Appropriateness of direct-acting oral anticoagulants dosing was assessed using US Food and Drug Administration guidelines. Data was analyzed using IBM® SPSS Version 26. 337 patients were included, with a mean age of 62.9±18.7 years. The majority were female (196, 58.3%). Of the patients, 194 (57.6%) received apixaban, 99 (29.4%) received rivaroxaban, and 44 (13.1%) received dabigatran. A total of 242 (71.8%) patients were prescribed direct-acting oral anticoagulants appropriately. Under-dosing and over-dosing were identified in 74 (22%) and 21 (6.2%) patients, respectively. Predictors of inappropriate dosing were age greater than 75 years (OR: 2.76, 95% CI: 1.67-4.56, p<0.001) and creatinine clearance less than 50 ml/minute (OR: 0.38, 95% CI: 0.19-0.74, p: 0.005). Inappropriate dosing was significantly associated with mortality (p=0.010).One-third of our patients received an inappropriate dose of direct-acting oral anticoagulants, mostly from underdosing. Elderly age and low creatinine clearance are significant predictors of inappropriate dose administration.