Afib Patients May Face Fewer Kidney Problems with Newer Anticoagulants

By Will Boggs MD

NEW YORK (Reuters Health) – Declining renal function is common in patients with atrial fibrillation (AF) who take oral anticoagulants, but the worsening seems to be less with non-vitamin K antagonist oral anticoagulants (NOACs) than with warfarin, according to a database study.

"We know that patients with atrial fibrillation face a high risk of kidney disease, and many AF patients have other risk factors that promote kidney function decline, such as advanced age, diabetes, and hypertension,” Dr. Xiaoxi Yao from Mayo Clinic, Rochester, Minnesota, told Reuters Health by email. “However, it is still surprising to me that nearly one in four patients on oral anticoagulation had a substantial decline of kidney function within just two years (at least a 30% decline in estimated glomerular filtration rate, eGFR).”

Dr. Yao and colleagues used data from the OptumLabs Data Warehouse to compare four oral anticoagulant agents - three NOACs (apaxiban, dabigatran, rivaroxaban) and warfarin – with respect to renal outcomes in 9,769 patients with AF (mean age, 72.6).

The findings were published online November 13 in the Journal of the American College of Cardiology.

Crude event rates per 100 person-years were 17.03 for an at least 30% decline in eGFR, 2.33 for doubling of serum creatinine, 8.50 for acute kidney injury (AKI), and 0.97 for kidney failure. Cumulative risks at the end of 2 years were 24.4%, 4.0%, 14.8%, and 1.7%, respectively.

When the three NOACs were pooled, they were associated with a 23% lower risk of eGFR decline, a 38% lower risk of serum creatinine doubling, and a 32% lower risk of AKI, compared with warfarin.

Individually, dabigatran was associated with significantly lower risks of eGFR decline and AKI; rivaroxaban with significantly lower risks of eGFR decline, serum creatinine doubling, and AKI; and apixaban with nonsignificantly lower risks of those same three outcomes.

Warfarin users with an average INR >3 had much higher rates of eGFR decline, serum creatinine doubling, and AKI, but even the warfarin-treated patients with lower mean INRs still appeared to have higher risks of these outcomes, compared with NOAC users.

“Since oral anticoagulation is a lifelong indication in most patients with AF, younger patients will be using oral anticoagulant drugs for a longer period of time and more likely to eventually have substantial decline in kidney function,” Dr. Yao explained. “Furthermore, an adverse event may have a larger impact on a young person’s life expectancy and quality of life, in comparison to a very old and sick person.”

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“Because kidney function decline is very common among AF patients treated with oral anticoagulants, physicians should regularly monitor renal function and make every effort to prevent and slow (it),” he said. “All NOACs rely on kidney for drug elimination, and they may require dose reduction when the kidney function declines to a certain extent.”

“When choosing which oral anticoagulants to use, the potential renal benefits of NOACs may need to be taken into consideration,” Dr. Yao said, cautioning that randomized trials are needed to confirm his team’s observational findings.

“For some patients,” he added, “NOACs may have a higher cost than warfarin, and the high cost could be a barrier to long-term adherence. Physicians should discuss the risk, benefit, and cost with patients and together make a decision.”

Dr. Lee Hebert from Ohio State University Wexner Medical Center, in Columbus, who recently reviewed anticoagulant-related nephropathy, told Reuters Health by email, "None of the trials to date have carefully studied renal function over time, especially in chronic kidney disease (CKD) patients. So, it would be ideal to have a prospective randomized trial in CKD patients in which the focus is on renal endpoints.”

“This was a nonrandomized comparison, so it can be confounded by unrecognized factors,” he said. “Of particular concern is that many, if not most, of the warfarin patients may not have been managed by point-of-care techniques, which are much more efficient and reliable.”

“The big advantage of warfarin is cost and the fact that reversal agents are readily available if massive hemorrhage is occurring,” Dr. Lee said. “If cost is no object and the patient is not optimally compliant, the NOACs would be preferable.”

Dr. Miho Kimachi from Graduate School of Medicine, Kyoto University, Japan, who recently reviewed anticoagulant use among AF patients with CKD, told Reuters Health by email, "I think it is greatly significant that this study indicated that NOACs reduced the risk of renal function decline in comparison with warfarin. It might not be amazing results, but I think that it is interesting because most studies did not show this association.”

“These findings might encourage physicians to prescribe NOACs, especially to patients at high risk of developing renal impairment,” she said. “However, we need to take care because this study has several issues, including a lack of power and selection bias (e.g., exclusion of patients without laboratory results).”

SOURCE: https://bit.ly/2zwKQsL

J Am Coll Cardiol 2017.

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