Dabigatran vs. Rivaroxaban for Nonvalvular Atrial Fibrillation

Oct 11, 2016
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Authors:
Graham DJ, Reichman ME, Wernecke M, et al.
Citation:
Stroke, Bleeding, and Mortality Risks in Elderly Medicare Beneficiaries Treated With Dabigatran or Rivaroxaban for Nonvalvular Atrial Fibrillation. JAMA Intern Med 2016;Oct 3:[Epub ahead of print].
Summary By:
Geoffrey D. Barnes, MD, MSc, FACC

Study Questions:

What are the comparative risks of thromboembolic stroke, intracranial hemorrhage (ICH), major extracranial bleeding, and mortality in elderly patients with nonvalvular atrial fibrillation (AF) who initiated dabigatran 150 mg twice daily or rivaroxaban 20 mg once daily?

Methods:

The authors examined claims for 118,891 fee-for-service Medicare patients with nonvalvular AF aged ≥65 years between November 4, 2011 and June 30, 2014. Baseline characteristic differences were adjusted with inverse probability weighting propensity scores. Adjusted hazard ratios (aHRs) were calculated for thromboembolic stroke, ICH, major extracranial hemorrhage, and mortality for rivaroxaban versus dabigatran therapy.

Results:

Among 52,240 dabigatran-treated and 66,651 rivaroxaban-treated patients (47% female), 2,537 primary outcome events occurred. Rivaroxaban use was associated with a nonsignificant reduction in thromboembolic stroke risk (aHR, 081; 95% confidence interval [CI], 0.65-1.01) or increase in mortality (HR, 1.15; 95% CI, 1.00-1.32). Rivaroxaban use was associated with an increase in major extracranial bleeding (HR, 1.48; 95% CI, 1.32-1.67; p < 0.001). In patients ≥75 years old and patients with a CHADS2 score >2, rivaroxaban use was associated with a significantly increased mortality compared to dabigatran use. The excess rate of ICH with rivaroxaban use exceeded the reduced rate of thromboembolic stroke.

Conclusions:

The authors concluded that among older AF patients, treatment with rivaroxaban 20 mg once daily was associated with a statistically significant increase in ICH and major extracranial bleeding risk as compared to dabigatran 150 mg twice daily.

Perspective:

There is a lack of head-to-head randomized trials between various direct oral anticoagulants. This is of particular importance given key differences in baseline patient characteristics between each of the pivotal phase III randomized trials. Therefore, this analysis of Medicare beneficiaries highlights important differences in treatment outcomes after adjusting for minor demographic and comorbidity differences. It is notable that dabigatran therapy was associated with a lower risk of ICH and major extracranial bleeding as compared to rivaroxaban. This is of particular importance given the minimal current use of dabigatran and widespread use of rivaroxaban. However, as with any observational study, unmeasured confounding cannot be adjusted for in the analysis. Therefore, additional observational studies confirming these results are needed in the absence of a true head-to-head randomized trial.

Keywords: Anticoagulants, Arrhythmias, Cardiac, Atrial Fibrillation, Geriatrics, Hemorrhage, Intracranial Hemorrhages, Medicare, Primary Prevention, Risk, Stroke, Thromboembolism, Treatment Outcome, Vascular Diseases


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