Impact of Hospitalization and Medication Switching on Post-discharge Adherence to Oral Anticoagulants in Atrial Fibrillation Patients

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 (AF). The aim of this study is to examine the impact of hospitalization and medication switching on post-discharge adherence to OACs in the AF population.

Methods

A quasi-experimental pre-post observational study was conducted using United States commercial insurance healthcare claims from the 2009-2016 OptumTM . AF adults taking OACs who had a random hospitalization occurring after the first observed OAC prescription fill and no other admission in the preceding and following six months were identified. OAC adherence was estimated by the proportion of days covered (PDC) within six and twelve months before and after hospitalization. Difference-in-difference (DID) analysis was employed to compare pre- and post-hospitalization PDCs, stratified by reasons for hospitalization (i.e., bleeding versus nonbleeding-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 1,029 (4.5%) of qualifying hospitalizations. After covariate adjustment, there was a reduction in PDC after discharge, regardless of admission diagnosis (p<0.0001). Six-month DID analyses revealed that adherence was incrementally reduced by 3.2% (p=0.0003) in the bleeding group compared to 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 to other switchers, regardless of the reason for hospitalization. Twelve-month DID 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.