Inappropriate dosing of direct oral anticoagulants in patients with atrial fibrillation.

Atrial fibrillation (AF) is a common cardiovascular disease for which newer oral anticoagulants are available. The main objective of this study was to evaluate the appropriateness in prescriptions of direct oral anticoagulant (DOACs), more specifically apixaban, dabigatran and rivaroxaban. This was a singlecentre, retrospective study conducted in the province of Quebec, Canada. Adult subjects hospitalized between October 2011 and October 2014, with a diagnosis of AF, and a DOAC prescription were included. Data were retrieved from the electronic medical records and prescriptions were evaluated according to appropriateness criteria. A total of 500 subjects were included (235 subjects on dabigatran,222 on rivaroxaban and 43 on apixaban). Overall, 70.4% (95% confidence interval [Cl] 66.4-74.1) of DOAC prescriptions were considered appropriate. About 24% of subjects received an inappropriate dose of apixaban, dabigatran or rivaroxaban. A reduced dose was prescribed in 56.8% of subjects with no clearindication, and 43.2% received a dose that was not reduced while indicated. DOACs were frequentlyprescribed at a dose that was considered inappropriate. There is a need to strengthen dosing recommendations of DOACs in clinical practice.