Study examines dosing for patients on dialysis with nonvalvular atrial fibrillation
Label-concordant dosing may benefit patients on dialysis with nonvalvular atrial fibrillation more than below-label dosing, according to data published in the American Journal of Kidney Diseases.
Further, warfarin correlated with an increased risk of bleeding compared with apixaban among this patient population.
“Some patients on dialysis who have atrial fibrillation receive apixaban for stroke prevention at a dose below that indicated by the official drug label to reduce adverse bleeding events,” James B. Wetmore, MD, MS, of the chronic disease research group at the Hennepin Healthcare Research Institute in Minnesota, and colleagues wrote. They added, “Given controversy about apixaban dosing in dialysis, we used data from the United States Renal Data System (USRDS) to examine the effectiveness and safety of apixaban based on whether it was dosed in accordance with its U.S. FDA label (5 mg twice daily) or off-label at a lower dose (2.5 mg twice daily, when 5 mg was actually indicated).”
In a retrospective cohort study, researchers evaluated data for 17,156 adults on dialysis who had atrial fibrillation and used either warfarin or apixaban between April 1, 2013, and Dec. 31, 2018. Researchers compared apixaban dosed according to the label, apixaban dosed below the label and warfarin to measure the correlation for each regimen with stroke prevention, major bleeding and death.
Using inverse-probability-of-treatment weighing, researchers balanced baseline patient characteristics across the three treatment groups and accounted for the possibility of differential loss to follow-up. Researchers also implemented analyses simulating an intention-to-treat approach and censoring at drug switch or discontinuation.
Analyses revealed no difference in risk of stroke among the label-concordant apixaban, below-label apixaban and warfarin treatment groups. Similarly, the label-concordant and below-label apixaban dosing correlated with a lower risk of major bleeding compared with warfarin in intention-to-treat analyses. However, below-label apixaban did not correlate with a lower bleeding risk when compared with label-concordant apixaban. Overall, label-concordant apixaban dosing correlated with a lower risk of mortality vs. warfarin, while there was no difference between below-label dosing of apixaban and warfarin.
“We found that apixaban, regardless of dosing strategy, was associated with lower risk of major bleeding than warfarin. When dosed in accordance with the label, apixaban appears to be associated with a lower risk of death compared with warfarin,” Wetmore and colleagues wrote. “There were no differences in stroke prevention among any of the three treatment approaches. Apixaban dosed in accordance with the label may provide the most favorable benefit/risk tradeoff in dialysis patients with atrial fibrillation.”