Oral Anticoagulant Prescription Trends, Profile Use, and Determinants of Adherence in Patients with Atrial Fibrillation

Background and Purpose Data on oral anticoagulant (OAC) uptake and pattern of use are limited. Real-life data in patients with atrial fibrillation (AF) are important for understanding patient exposure. A cohort study of new OAC users was built to assess trends of drug use from 2011 to 2017, persistence rate, switching rate, adherence level, and predictors of adherence. Methods We built a cohort using the Regie d'Assurance Maladie du Quebec (RAMQ) and Med-Echo administrative databases of new adult OAC users within 1 year following hospitalization with a diagnosis of AF. New users of OAC were defined as having no OAC claims in the year before cohort entry. We assessed trends of OAC use; persistence rate, defined as a gap between refills of no longer than two times the duration of the previous prescriptions; and adherence level, defined as the proportion of days covered (PDC) over a 1-year period following initiation. Predictors of nonadherence (PDC less than 80%) were analyzed using logistic regression models. Results The cohort consisted of 33,311 incident OAC users. Of total OAC claims, the proportions of warfarin claims decreased from 77.9% in 2011 to 12.7% in 2017, with direct oral anticoagulants (DOACs) accounting for 87.3% of claims, of which apixaban and rivaroxaban accounted for 60.1% and 23.4%, respectively, by the end of 2017. One year after OAC initiation, persistence rates ranged from 53% with warfarin to 77% with a high dose of apixaban. Approximately 75% of incident OAC users were considered "adherent" (PDC 80% or more), with a mean PDC of 95.6-98.1%, compared with "nonadherent," with a mean PDC varying between 43.1% and 50.7%. Older age, female sex, higher CHA(2)DS(2)-VASc score (to predict thromboembolic risk in AF), prior stroke, and treatment with chronic cardiovascular disease drugs were associated with high adherence levels. Conclusion The clinical uptake of DOACs increased over time, accounting for 87.3% of prescriptions in 2017. In our study, 25% of new OAC users presented a low adherence level. Adherence to OACs remains a significant challenge in patients with AF.