Prevalence and Predictors of Nonadherence to Direct Oral Anticoagulant Treatment in Patients with Atrial Fibrillation

Background  For most patients with newly diagnosed atrial fibrillation (AF), direct oral anticoagulants (DOACs) are preferred over vitamin K antagonists. However, there is concern that the lack of monitoring may impair therapy adherence and therefore the anticoagulant effect. Objective  To assess 1-year DOAC nonadherence in patients with AF and a treatment indication of at least 1 year in the Dutch health care setting, and to identify predictors of nonadherence. Methods  We performed a near-nationwide historical cohort study in patients with a novel DOAC indication for AF. Data were obtained from a pharmacy database, covering 65% of all outpatient prescriptions dispensed in the Netherlands. The 1-year nonadherence was assessed by the proportion of days covered; the threshold was set at <80%. Robust Poisson regression analyses were performed to identify predictors of nonadherence. Results  A total of 46,211 patients were included and the 1-year nonadherence was 6.5%. We identified male sex (risk ratio [RR] 1.23, 95% confidence interval [CI]: 1.15-1.33), younger age (age ≥60 to <70 years: RR: 1.15, 95% CI: 1.00-1.33, age <60 years: RR: 2.22, 95% CI: 1.92-2.57; reference age ≥85 years), a reduced DOAC dose (RR: 1.10, 95% CI: 1.00-1.22), a twice-daily dosing regimen (RR: 1.21, 95% CI: 1.12-1.30), and treatment with apixaban (RR: 1.16, 95% CI: 1.06-1.26, reference rivaroxaban) or dabigatran (RR: 1.25, 95% CI: 1.14-1.37) as independent predictors of 1-year nonadherence. Conclusion  One-year nonadherence to DOACs was low yet relevant in patients with AF newly prescribed a DOAC. Understanding the predictors for nonadherence may help identify patients at risk.