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 Régie d'Assurance Maladie du Québec (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 DS -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.