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.