Background: Adherence to chronic medications remains poor in practice. There is limited evidence on how hospitalization affects post-discharge adherence to oral anticoagulants (OACs) in individuals with atrial fibrillation. The aim of this study was to examine the impact of hospitalization and medication switching on post-discharge adherence to OACs in the population with atrial fibrillation.
Methods: A quasi-experimental pre-post observational study was conducted using United States commercial insurance health care claims from the 2009 to 2016 Optum database. Adults with atrial fibrillation taking OACs who had a random hospitalization occurring after the first observed OAC prescription fill and no other admission in the preceding and following 6 months were identified. OAC adherence was estimated by the proportion of days covered within 6 and 12 months before and after hospitalization. Difference-in-difference analysis was employed to compare the pre-hospitalization and post-hospitalization proportion of days covered, stratified by reasons for hospitalization (i.e., bleeding vs non-bleeding-related reasons) and adjusting for imbalanced baseline characteristics between groups. Change in adherence when the OAC was switched at discharge was also examined.
Results: The 22,429 individuals who met study criteria were predominantly male (52.4%), white (77.2%), and older age (median 74 years). A clinically significant hemorrhage was the reason for 1029 (4.5%) of qualifying hospitalizations. After covariate adjustment, there was a reduction in the proportion of days covered after discharge, regardless of admission diagnosis (p<0.0001). The 6-month difference-in-difference analyses revealed that adherence was incrementally reduced by 3.2% (p=0.0003) in the bleeding group compared with the nonbleeding group, whereas switching from warfarin to a direct oral anticoagulant after hospitalization was associated with a smaller reduction by 3.4% in adherence (p=0.0342) compared with other switchers, regardless of the reason for hospitalization. The 12-month difference-in-difference analyses revealed similar results.
Conclusions: Hospitalization is temporally associated with a reduction in adherence to OACs, regardless of reason for hospitalization. More effective strategies are needed to improve OAC adherence, particularly during transition of care.
Keywords: atrial fibrillation; cardiovascular therapy; collaborative care; medication adherence; oral anticoagulant; pharmacoepidemiology.; stroke prevention.
© 2020 Pharmacotherapy Publications, Inc.