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Among patients with similar renal function, treatment for kidney failure was more likely in younger patients than in their older counterparts, a retrospective study out of Canada showed.

This held true across the range of estimated glomerular filtration rate (eGFR), according to Brenda Hemmelgarn, MD, PhD, of the University of Calgary in Alberta, and colleagues.

For example, in the patients with the worst kidney function (eGFR of 15 to 29 mL/min/1.73 m²), the adjusted rate of treated kidney failure was 24 per 1,000 person-years among those ages 18 to 44 and 1.53 per 1,000 person-years among those age 85 and older (P<0.001, 95% CI 0.59 to 3.99).

Conversely, among those with the worst kidney function at baseline, rates for the oldest compared with the youngest patients were 19.95 (95% CI 15.79 to 25.19) versus 3.53 (95% CI 1.56 to 8.01) per 1,000 person-years, respectively (P<0.001).

These results, reported in the June 20 issue of the Journal of the American Medical Association, "suggest that the incidence of advanced kidney disease in the elderly may be substantially underestimated by rates of treated kidney failure alone and that untreated kidney failure may be more common than initiation of renal replacement at older ages," the authors wrote.

"These findings have important implications for clinical practice and decision making," they continued. "Coupled with the finding that many older adults with advanced chronic kidney disease are not adequately prepared for dialysis, these results suggest a need to prioritize the assessment and recognition of chronic kidney disease progression among older adults."

Previous studies of kidney failure among older adults have focused on the receipt of dialysis, a measure of both disease progression and treatment decisions. That can underestimate the actual burden of disease, however, because it leaves out the patients who do not receive treatment.

To explore the relationship between age and rates of treated and untreated kidney failure, the researchers retrospectively looked at data from more than 1.8 million adults living in Alberta who had their kidney function measured from May 2002 to March 2008. All had an eGFR of 15 mL/min/1.73 m² or higher and did not require renal replacement therapy at baseline.

The main outcomes were treated kidney failure (receipt of either dialysis or a kidney transplant), untreated kidney failure (progression to an eGFR of less than 15 mL/min/1.73 m² without renal replacement therapy), and all-cause death.

Through a median follow-up of 4.4 years, 5.36% of the patients died, 0.18% developed kidney failure that was treated, and 0.17% developed kidney failure that was untreated.

The study "highlights a potentially sizable unmeasured burden of untreated kidney failure among older adults," Manjula Kurella Tamura, MD, MPH, and Wolfgang Winkelmayer, MD, MPH, of Stanford University in Stanford, Calif., wrote in an accompanying editorial.

"It is of paramount importance to refine the current understanding of what constitutes appropriate treatment for kidney failure, which factors influence the decision-making process, and which methods are optimal for aligning treatment plans with patient goals and prognosis," they wrote.

Hemmelgarn and colleagues acknowledged some limitations of the study, including the inability to assess the reasons for not receiving treatment, the exclusion of patients who did not have at least one serum creatinine measurement, and the lack of long-term follow-up to look for clinical events.

The study was supported by the Canadian Institutes of Health Research (CIHR) and by an interdisciplinary team grant from Alberta Innovates-Health Solutions (AI-HS). Hemmelgarn and two of her co-authors were supported by career salary awards from AI-HS. Hemmelgarn was supported by the Roy and Vi Baay Chair in Kidney Research. Her co-authors reported additional support from a Government of Canada Research Chair and Fellowship Awards from CIHR and the Canadian Diabetes Association.

Hemmelgarn reported that she had no conflicts of interest. Her co-authors reported relationships with UpToDate and Amgen.

Kurella Tamura is supported by a Paul B. Beeson Award from the National Institute on Aging. She reported having served as a scientific advisor to Amgen. Winkelmayer reported having served as a scientific advisor to Affymax/Takeda, Amgen, Fibrogen/Astellas, GlaxoSmithKline, and Vifor Fresenius Medical Care Renal Pharma Ltd.

Primary source:Journal of the American Medical Association
Source reference:
Hemmelgarn B, et al "Rates of treated and untreated kidney failure in older versus younger adults" JAMA 2012; 307:2507-2515.

Additional source: Journal of the American Medical Association
Source reference:
Kurella Tamura M, Winkelmayer W "Treated and untreated kidney failure in older adults: what's the right balance?" JAMA 2012; 307: 2545-2546.

Todd Neale

Senior Staff Writer

Todd Neale, MedPage Today Staff Writer, got his start in journalism at Audubon Magazine and made a stop in directory publishing before landing at MedPage Today. He received a B.S. in biology from the University of Massachusetts Amherst and an M.A. in journalism from the Science, Health, and Environmental Reporting program at New York University. He is based at MedPage Today headquarters in Little Falls, N.J.

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