Study Shows Pharmacist Support Key in Medication Adherence for Veterans Prescribed Dabigatran for Atrial Fibrillation
Atrial fibrillation is the most common cardiac arrhythmia, necessitating treatment with oral anticoagulation in moderate- to high-risk patients to reduce the risk of stroke. Warfarin was the only treatment available until the recent introduction of target-specific oral anticoagulants. Dabigatran is the first of several in this class approved in the U.S., and, unlike warfarin, does not require routine testing to evaluate anticoagulation effect. However, a previous study reported that suboptimal adherence to dabigatran was associated with increased risk of stroke and death. This mixed-methods retrospective study assessed site-level variation in dabigatran adherence and identified practices associated with higher dabigatran adherence within the VA healthcare system. Using VA data, investigators identified 4,863 Veterans with non-valvular atrial fibrillation who filled dabigatran prescriptions at 67 VAMCs between 2010 and 2012. Interviews were then conducted with anticoagulation or outpatient clinic supervisors, or senior pharmacists at 41 sites. The primary outcome was patient adherence to dabigatran defined by proportion of days covered (ratio of days supplied by prescription to follow-up duration) of 80% or more.
- Among VA patients who were treated with dabigatran, there was significant site-level variation in medication adherence across VAMCs – with the site average ranging from 42% to 93%.
- Veterans were more likely to be adherent and without missing doses when they were monitored by VA pharmacists.
- Longer duration of pharmacist-led monitoring and providing more intensive care to non-adherent patients, in collaboration with the clinician, also improved medication adherence.
- Findings suggest extra patient support (i.e., pharmacist availability) may significantly improve adherence to dabigatran.
- These data affirm that VA's rich infrastructure of pharmacist-led, specialized anticoagulation care may continue to have an important role in maximizing safety, effectiveness, and appropriate use of these new agents, even as warfarin use continues to decline.
- Data on practice patterns were evaluated based on interview responses without direct observation.
- Study conclusions regarding role of pharmacist were limited by lack of a randomized control group.
- Investigators could not obtain data on all eligible sites, highlighting potential misclassification bias.
- Some covariates had small numbers, making it difficult to estimate their influence on patient adherence to dabigatran.
- This study assumed that all patients refilled dabigatran at VA pharmacies and did not have access to Medicare data for refills outside VA. However, analyses have shown the use of Medicare benefits for dabigatran among VA users is very low, due to higher, tiered copayments in Medicare.
Shore S, Ho P, Lambert-Kerzner A, Glorioso T, Carey E, Cunningham F, Longo L, Jackevicius C, Rose A, and Turakhia M. Site-Level Variation in and Practices Associated with Dabigatran Adherence. JAMA. April 14, 2015;313(14):1443-50.