Clinical Investigation
Electrophysiology
Adherence to dabigatran therapy and longitudinal patient outcomes: Insights from the Veterans Health Administration

https://doi.org/10.1016/j.ahj.2014.03.023Get rights and content

Background

Dabigatran is a novel oral anti-coagulant (NOAC) that reduces risk of stroke in patients with non-valvular atrial fibrillation (NVAF). It does not require routine monitoring with laboratory testing which may have an adverse impact on adherence. We aimed to describe adherence to dabigatran in the first year after initiation and assess the association between non-adherence to dabigatran and clinical outcomes in a large integrated healthcare system.

Methods

We studied a national cohort of 5,376 patients with NVAF, initiated on dabigatran between October-2010 and September-2012 at all Veterans Affairs hospitals. Adherence to dabigatran was calculated as proportion of days covered (PDC) and association between PDC and outcomes was assessed using standard regression techniques.

Results

Mean age of the study cohort was 71.3 ± 9.7 years; 98.3% were men and mean CHADS2 score was 2.4 ± 1.2 (mean CHA2DS2VASc score 3.2 ± 1.4). Median PDC was 94% (IQR 76%-100%; mean PDC 84% ± 22%) over a median follow-up of 244 days (IQR 140-351). A total of 1,494 (27.8%) patients had a PDC <80% and were classified as non-adherent. After multivariable adjustment, lower adherence was associated with increased risk for combined all-cause mortality and stroke (HR 1.13, 95% CI 1.07–1.19 per 10% decrease in PDC). Adherence to dabigatran was not associated with non-fatal bleeding or myocardial infarction.

Conclusions

In the year after initiation, adherence to dabigatran for a majority of patients is very good. However, 28% of patients in our cohort had poor adherence. Furthermore, lower adherence to dabigatran was associated with increased adverse outcomes. Concerted efforts are needed to optimize adherence to NOACs.

Section snippets

Study design, setting and population

This is a retrospective cohort study of patients receiving health care in the VA between October 1, 2010 and September 30, 2012. We included all patients who filled a dabigatran prescription of at least 30 days duration at a VA pharmacy and had at least 30 days of follow-up. During this time, the criteria for dabigatran use were based on national, standardized VA Pharmacy Benefits Management criteria8 which included patients with non-valvular atrial fibrillation and a CHADS2 or CHA2DS2-VASc

Baseline characteristics

We initially identified 6,335 patients receiving at least one new dabigatran prescription between October 1, 2010 and September 30, 2012 (Figure 2). After applying our eligibility criteria, 959 (15.1%) patients with less than 30 days of follow-up and/or less than 30 days of medication fill were excluded. A total of 5,376 (84.9%) patients were included in the final study cohort with a median follow-up period of 244 days (IQR 140 - 351) and median of 5 refills (IQR 2-8) in the first year of

Discussion

The objective of this study was to describe adherence and its association with clinical outcomes in a national cohort of Veterans treated with dabigatran. We found that in patients with non-valvular atrial fibrillation, adherence to dabigatran in the first year was good for a majority of patients. However, more than one-quarter of patients had sub-optimal adherence to dabigatran and poor adherence was associated with an increased risk for stroke and all-cause mortality. There was no association

Disclaimer

The views expressed in this article are those of the authors and do not represent the United States government.

Disclosures

Funding sources: No funding agencies were involved in the design and conduct of the study; collection, management, analysis, and interpretation of the data; or preparation, review, and approval of the manuscript.

Conflicts of Interest disclosures: Drs. Bradley, Turakhia and Maddox are supported by Career Development Awards from Veterans Affairs Health Services Research & Development. All the other authors report no relevant disclosures.

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