Dabigatran lowers acute kidney injury risk vs. warfarin in nonvalvular AF

In a large Asian cohort of patients with nonvalvular atrial fibrillation, those treated with dabigatran had a lower risk for acute kidney injury than those treated with warfarin, according to new data.

“This is the first and largest population-based study to investigate the risk of acute kidney injury from oral anticoagulants with a specific focus on Asians with nonvalvular AF taking dabigatran or warfarin during the same period,” Yi-Hsin Chan, MD, from the cardiovascular department, Chang Gung Memorial Hospital in Linkou, Taoyuan, Taiwan, and colleagues wrote.

The researchers studied patients with new-onset nonvalvular AF who were enrolled in a Taiwan nationwide retrospective cohort study from 1996 to 2013.

The researchers identified 7,702 patients with no history of chronic kidney disease (CKD) assigned dabigatran (Pradaxa, Boehringer Ingelheim) and 7,885 patients with no history of CKD assigned warfarin, as well as 2,256 patients with CKD assigned dabigatran and 2,089 patients with CKD assigned warfarin.

There was a median follow-up of 0.69 years for participants assigned dabigatran and 0.79 years for warfarin users.

Of those assigned dabigatran, 88% of those without CKD and 90% of those with CKD were prescribed the 110-mg twice-daily dose; the rest received the 150-mg twice-daily dose.

Consistently lower risk

Chan and colleagues found that dabigatran was linked to lower acute kidney injury risk than warfarin for those without CKD (HR = 0.62; 95% CI, 0.49-0.77) and those with CKD (HR = 0.56; 95% CI, 0.46-0.69).

In the dabigatran group, there was not a strong relationship between CHA₂DS₂-VASc score and acute kidney injury, but in the warfarin group, incidence of acute kidney injury rose markedly with increase in CHA₂DS₂-VASc score (CKD-free group: CHA₂DS₂-VASc score of 0 or 1, 2% per year; CHA₂DS₂-VASc score of 6 or more, 6.16% per year; CKD group: CHA₂DS₂-VASc score of 0 or 1, 6.82% per year; CHA₂DS₂-VASc score of 6 or more, 26.03% per year), according to the researchers.

The annual risk for acute kidney injury was significantly higher in the warfarin group compared with the dabigatran group for those with a high CHA₂DS₂-VASc score ( 4 for the CKD-free cohort and 3 for the CKD cohort), Chan and colleagues wrote.

In a subgroup analysis, the researchers found that, among dabigatran users, those assigned low-dose or standard-dose dabigatran, those with a warfarin-naive or warfarin-experienced history, those with or without diabetes, and those with CHA₂DS₂-VASc 4 or HAS-BLED 3 had a decreased risk for acute kidney injury compared with patients in the warfarin cohort.

Further study needed

In a related editorial, Sergey V. Brodsky, MD, PhD, and Lee A. Hebert, MD, from The Ohio State University Wexner Medical Center, Columbus, wrote that the findings “provide strong evidence that incident [acute kidney injury] is a big problem in patients with [AF] who are receiving warfarin and dabigatran.”

However, according to Brodsky and Hebert, anticoagulant-related nephropathy requires further study. “Clearly, the only path to the truth is a rigorous prospective study of patients who are initiating anticoagulant therapy. The work by Chan et al provides strong incentive for such an endeavor.” – by Dave Quaile

Disclosure: The researchers, Brodsky and Hebert report no relevant financial disclosures.