Assessment of Patient Adherence to Direct Oral Anticoagulant vs Warfarin Therapy

Direct oral anticoagulants (DOACs) may be as effective as, and at times safer than, warfarin. Because DOACs do not require regular serum level monitoring, patients' interaction with the health care system may be reduced. To the authors' knowledge, although studies have evaluated warfarin adherence, few studies have evaluated the real-world adherence to DOACs.

To evaluate whether a difference exists between medication adherence of patients taking DOACs vs patients taking warfarin.

The electronic medical records of the Anticoagulation Clinic database at Mayo Clinic in Scottsdale, Arizona, were reviewed. Inclusion criteria were adults taking DOACs and a matching cohort taking warfarin between January 1, 2011, and December 30, 2013. The Morisky Medication Adherence Scale-8 item, a validated medication adherence tool, was used to evaluate adherence in both cohorts, and the qualitative covariates were analyzed using ordinal logistic regression.

Of 324 surveys that were sent, 110 patients (34.0%) responded. Most patients took DOACs for atrial fibrillation, and few took DOACs for venous thromboembolism. Overall, 60 of 66 patients (90.9%) in the DOAC group and 42 of 44 patients (95.5%) in the warfarin group reported medium or high adherence. Difference in adherence scores between the 2 groups was not statistically significant (P=.8).

Similar adherence was noted between DOACs and warfarin regardless of the frequency of serum level monitoring.