Group based trajectory modeling to assess adherence to oral anticoagulants among atrial fibrillation patients with comorbidities: a retrospective study

Background Poor adherence to oral anticoagulants is a significant problem in atrial fibrillation (AF) patients with comorbidities as it increases the risk for cardiac and thromboembolic events. Aim The primary objective was to evaluate adherence to direct oral anticoagulants (DOACs) or warfarin using group-based trajectory modeling (GBTM). The secondary objective was to identify the predictors of adherence to oral anticoagulants. Finally, to report the drug interactions with DOACs/warfarin. Method This retrospective study was conducted among continuously enrolled Medicare Advantage Plan members from January 2016-December 2019. AF patients with comorbid hypertension, diabetes and hyperlipidemia using warfarin/DOACs were included. Monthly adherence to DOAC/warfarin was measured using proportion of days covered (PDC) and then modeled in a logistic GBTM to identify the distinct patterns of adherence. Logistic regression model was conducted to identify the predictors of adherence to oral anticoagulants adjusting for all baseline characteristics. Concomitant use of DOACs/warfarin with CYP3A4,P-gp inhibitors were measured. Results Among 317 patients, 137 (43.2%) and 79 (24.9%) were DOAC, and warfarin users, respectively. The adherence trajectory model for DOACs included gradual decline (40.4%), adherent (38.8%), and rapid decline (20.8%). The adherence trajectories for warfarin adherence included gradual decline (8.9%), adherent (59.4%), and gaps in adherence (21.7%). Predictors of adherence included type of oral anticoagulant, stroke risk score, low-income subsidy, and baseline PDC. CYP3A4,P-gp drugs were co-administered with DOACs /warfarin resulting in adverse events. Conclusion Adherence to oral anticoagulants is suboptimal. Interventions tailored according to past adherence trajectories may be effective in improving patient's adherence.