QUANTITATIVE ASSESSMENT OF DIRECT ORAL ANTICOAGULANT ADHERENCE USING THE PROPORTION OF DAYS COVERED METHOD

Background: Non-adherence to direct oral anticoagulant (DOAC) therapy in patients with atrial fibrillation and flatter (AFF) can compromise treatment effectiveness, increasing the risk of stroke and other complications. Evaluation of non-adherence is essential to optimize treatment and minimize the risk of negative outcomes.
Aim: This study aimed to assess DOAC therapy adherence among patients with AFF based on data from the National Health Service’s reimbursement prescriptions database.
Method: A retrospective study was conducted using the prescriptions database from January 2012 to December 2022. The investigation included prescriptions with diagnoses of atrial fibrillation and flutter. Adherence was calculated for patients with at least two DOAC prescriptions, including rivaroxaban, dabigatran, edoxaban, or apixaban. The Proportion of Days Covered method
was used to evaluate medication adherence by calculating the proportion of days in a given period that a patient has access to their prescribed medication. Higher PDC values signify higher medication adherence. The optimal adherence level was defined as 80% or higher.
Results: Adherence to DOAC therapy was evaluated in 45,933 patients with an average age of 75.0 years (SD = 9.6). Of these patients, 27,355 (59.6%) were female. Overall adherence was 69.4%, with respective adherence rates of 70.7% for rivaroxaban, 69.4% for dabigatran, 64.5% for edoxaban, and 45.8% for apixaban. Only 44.2% of patients maintained adherence levels above 80%. Significant changes in adherence were noted when patients switched between
different DOACs (p\ 0.001), but adherence levels for each specific drug remained consistent among those who switched (p = 0.577).
Conclusion: Adherence to DOAC therapy was considered low because less than half of the patients achieved optimal adherence levels. These findings underscore the need for tailored interventions to improve patient adherence.