Non-vitamin K antagonist oral anticoagulant (NOAC) use and dosing in Canadian practice: Insights from the optimising pharmacotherapy in the management approach to lowering risk in atrial fibrillation (OPTIMAL AF) Programme

Aims To estimate the rate of non-vitamin K oral anticoagulant (NOAC) dosing that is lower- and higher-than-recommended and to describe the reasons for NOAC dose discordance with Health Canada prescribing information. Methods The OPTIMAL AF Programme was an observational cohort quality assessment initiative in which primary and specialty care physicians in eight provinces provided a snapshot of their anticoagulated non-valvular atrial fibrillation (NVAF) patients through either an electronic medical record (EMR) system or standardised, paper-based data collection methods. Results Data on 1681 NVAF patients receiving oral anticoagulation (OAC) for stroke prevention was provided by 102 physicians. A NOAC was prescribed in 1379 patients (8%). The standard recommended dose was prescribed in 849 (76%) and reduced dose in 264 (24%). Concordance of the reduced dose with Health Canada prescribing information occurred in 154 patients (58%). The standard dose was concordant in 805 (95%). The main reasons for the use of discordant reduced doses were age of 80 years or more, elevated creatinine, prior bleeding or dose recommended by specialist. Discussion and Conclusion The vast majority of Canadian patients meeting the Canadian Cardiovascular Society (CCS) guideline recommendations for OAC to decrease AF-related stroke risk were receiving product monograph-concordant NOAC dosing (85%). Nonetheless, this highlights the fact that an important proportion of patients were prescribed doses that are discordant and opportunities remain to improve NOAC dosing to optimise stroke prevention.