Inappropriate non-vitamin K antagonist oral anticoagulants prescriptions: be cautious with dose reductions

Background Non-vitamin K antagonist oral anticoagulants (NOACs) are prescribed to patients with atrial fibrillation (AF) to reduce the risk of stroke. Prescribing the correct dose warrants careful consideration of the prevailing dose criteria that differ per NOAC. Electronic systems are useful to intercept prescriptions that are incorrect based on simple 'primary' criteria, for example dosing frequency and drug-drug interactions with concomitant medication. However, these systems do not take into account patient characteristics such as age, renal function or weight, which are crucial elements to determine the NOAC dose.

Methods Our goal was to determine the appropriateness of all prescriptions, as compared with the product labelling approved by the European Medicines Agency, to address common pitfalls in prescribing NOACs. AF patients with a first NOAC prescription between January 2012 and December 2016 were identified from our electronic hospital information system (Martini Hospital, Groningen, the Netherlands).

Results The study included 3,231 AF patients who had started on an NOAC; 10.7% received an inappropriate dose and the appropriateness of the prescription could not be determined in 14.1%. Underdosing and overdosing occurred in 5.4% and 4.5% of all prescriptions, respectively. A reduced-dose NOAC was a predictor for incorrect prescribing (odds ratio: 2.70, 95% confidence interval: 2.13-3.41). Patient factors were identified that predicted incorrect prescriptions for dabigatran and apixaban.

Conclusion An incorrect prescription occurred more often in the reduced-dose NOAC group. Clinical parameters such as renal function are often unknown whilst these are essential to determine the right NOAC and dose.