Is the prescription right? A review of non-vitamin K antagonist anticoagulant (NOAC) prescriptions in patients with non-valvular atrial fibrillation. Safe prescribing in atrial fibrillation and evaluation of non-vitamin K oral anticoagulants in stroke prevention (SAFE-NOACS) group

Abstract

Background: Non-vitamin K antagonist oral anticoagulants (NOACs) are a major advance for stroke prevention in atrial fibrillation (AF). Use of the vitamin K antagonist (VKA), warfarin, has dropped 40% since 2010 in our institution. There is limited Irish hospital data on NOAC prescribing for stroke prevention. Method: Single centre, retrospective observational cohort study of consecutive AF patients at increased risk of stroke and/or awaiting electrical cardioversion. Data on prescribed NOACs from February 2010 till July 2015 was collected from the electronic inpatient record. Appropriateness of prescriptions was based on CHA2DS2–VASC score and accuracy on individual NOAC SPCs. Potential drug interactions and bleeding risk were also quantified. Results: A total of 348 patients AF and increased risk of stroke (CHA2DS2–VASC score > 1 for men and > 2 for women) were studied. Forty-eight percent were female with a mean age 71 ± 18.6 years, 52% of whom were > 75. Mean CHA2DS2-Vasc and HAS-BLED scores were 4.1 ± 1.8 and 1.4 ± 0.8, respectively. Rivaroxaban, dabigatran and apixaban were prescribed to 154 (54.2%), 106 (34.3%) and 41 (13.2%) patients, respectively. 20.4% had inaccurate prescriptions; 92.9% (n = 65) underdosed and 7.1% (n = 5) on inappropriately higher doses. Neither choice of NOAC, age, history of anaemia, previous bleeding or co-prescribed antiplatelets influenced the accuracy of prescription (p = NS), but decreased renal function appeared to do so (p = 0.05). Conclusion: Our study highlights significant inaccuracies in NOAC prescribing. Patients commenced on NOACs should be assessed and followed up in a multidisciplinary AF clinic to ensure safe and effective prescribing and stroke prevention.