Trajectories of Oral Anticoagulation Adherence Among Medicare Beneficiaries Newly Diagnosed With Atrial Fibrillation

BACKGROUND: Only 50% of atrial fibrillation (AF) patients recommended for oral anticoagulation (OAC) use these medications, and less than half of them adhere to OAC. In a cohort of Medicare beneficiaries newly diagnosed with AF, we identified groups of patients with similar trajectories of OAC use and adherence, and evaluated patient characteristics affecting group membership. METHODS AND RESULTS: We selected continuously enrolled Medicare Part D beneficiaries with first AF diagnosis in 2014 to 2015 (n=34 898). We calculated the proportion of days covered with OAC over the first 12 months after diagnosis and identified OAC adherence trajectories using group‐based trajectory models. We constructed multinomial logistic regression models to evaluate how demographics, system‐level factors, and clinical characteristics were associated with group membership. We identified 4 trajectories of OAC adherence: patients who never used OAC (43.8%), late OAC initiators (7.6%), early OAC discontinuers (8.9%), and continuously adherent patients (40.1%). Predictors such as sex, black race, residence in the South, or HAS‐BLED score were associated with not only OAC use, but also the timing of initiation and the likelihood of discontinuation. For example, HAS‐BLED score ≥4 was associated with a higher likelihood of not using OAC (odds ratio 1.35; 95% CI, 1.14–1.62), of late initiation (1.55; 95% CI, 1.11–2.05), and of early discontinuation (odds ratio 1.35; 95% CI, 1.01–1.84). CONCLUSIONS: We identified 4 distinct trajectories of OAC adherence after first AF diagnosis, with <45% of newly diagnosed AF patients belonging to the trajectory group characterized by continuous OAC adherence. Trajectories were associated not only with demographic and clinical characteristics but also with regional factors.