DOES HOSPITALIZATION FOR THROMBOEMBOLISM IMPROVE ORAL ANTICOAGULANT ADHERENCE IN ATRIAL FIBRILLATION PATIENTS

ABSTRACT Objectives It is not known how medication adherence changes after hospitalization for a sentinel thromboembolic event. The purpose of this study is to examine the impact of hospitalization for ischemic stroke or thromboembolism on post-discharge adherence to oral anticoagulants in atrial fibrillation patients. Design We conducted a quasi-experimental pre-post observational study using a large U.S. commercial insurance healthcare claims database. Setting and participants: Adult atrial fibrillation patients taking oral anticoagulants with a random hospitalization for a nonbleeding-related reason occurring after the first observed oral anticoagulant prescription fill, with no other admissions within the preceding and following six months, were identified in OptumTM ClinformaticsTM from 2009-2016. Outcome measures Adherence was estimated by the proportion of days covered within six and twelve months before and after hospitalization. Difference-in-difference analysis via a generalized linear model was employed to compare pre- and post-hospitalization proportions of days covered by reasons for hospitalization (i.e., ischemic stroke/thromboembolism versus other nonbleeding-related reasons), adjusting for imbalanced baseline characteristics. Results Of the 21,400 individuals meeting inclusion criteria, 5.4% were hospitalized for ischemic stroke/thromboembolism, and 94.6% for other nonbleeding-related reasons. Baseline characteristics were quite similar between groups, except for a few covariables such as age or CHA2DS2-VASc score. Minority race/ethnicity individuals had 0.7% lower overall PDC as compared to whites (p=0.006). After covariate adjustment, 6-month adherence declined by 1.1% less in individuals hospitalized for ischemic stroke/thromboembolism, compared to other nonbleeding reasons, even though the difference was not statistically significant (p=0.17). Similar results were observed for the 12-month window. Conclusion This real-world study suggests that more effective strategies are needed to improve adherence to oral anticoagulant, particularly after a thromboembolic event.