The following is the summary of “Apixaban Dosing Patterns Versus Warfarin in Patients With Nonvalvular Atrial Fibrillation Receiving Dialysis: A Retrospective Cohort Study” published in the November 2022 issue of American Journal of Kidney Diseases by Wetmore, et al.
Patients with nonvalvular atrial fibrillation (AF) on dialysis have a lack of well-defined comparisons of clinical outcomes among anticoagulation regimens employing various dosages of apixaban or warfarin. Results were compared in this study between a national cohort of patients in the United States receiving continuous dialysis for renal failure. Research Methodology Historical cohort study. Treatment of atrial fibrillation (AF) with apixaban or warfarin in dialysis patients is documented in the US Renal Data System database between 2013 and 2018. Initial therapy with either apixaban at the labeled dose, a lower dose of apixaban, or warfarin. The results are ischemic stroke/systemic embolism, significant hemorrhage, and death from any cause.
Inverse probability weighting Cox proportional hazards models. There were also censoring at drug switch or discontinuance (CAS) analyses and those that mimicked an intention-to-treat (ITT) method. To accommodate for potential informative censoring, an inverse probability of censoring weighting strategy was implemented. There was no significant difference in the risk of stroke/systemic embolism between the groups treated with warfarin, apixaban, or apixaban below labeling among 17,156 people. In ITT analyses, apixaban was associated with a decreased risk of serious bleeding compared with warfarin at both label-concordant and below-label doses (HR, 0.67 [95% CI, 0.55-0.81] and HR, 0.68 [95% CI, 0.55-0.84]). Apixaban used off-label did not reduce bleeding risk as compared to label-concordant apixaban (hazard ratio [HR], 1.02 [95% CI, 0.78-1.34]). When comparing apixaban with warfarin, label-concordant dose was associated with a decreased risk (HR, 0.85 [95% CI, 0.78-0.92]) but below-label dosing showed no significant difference (HR, 0.97 [95% CI, 0.89-1.05]). The CAS analysis yielded generally consistent findings.
The study was restricted to Medicare recipients in the United States; outcomes of atrial fibrillation, stroke, and hemorrhage were derived from administrative claims; likely residual confounding existed. When comparing warfarin and apixaban, the risk of bleeding in patients with nonvalvular AF undergoing dialysis is higher for warfarin. No significant difference in bleeding risk was observed between doses of apixaban that were below and above the recommended range. Apixaban has been shown to reduce mortality compared to warfarin when dosed in accordance with the drug’s label. Nonvalvular atrial fibrillation (AF) patients on dialysis may find the best benefit-risk balance with label-concordant dose rather than reduced-label dosing.