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The kidney donor pool can be expanded with little risk to donors or recipients, new research suggested.

One study showed that living donors — considered the best option for most patients with kidney failure — likely had a similar risk for hypertension and albuminuria after donation as nondonors, while the other study showed that recipients of kidneys from donors who underwent dialysis likely faced delayed graft function but not higher risks for graft failure or death.

Both studies, along with related editorials, were published online in JAMA.

Little Hypertension Risk for Healthy Donors

To assess hypertension and kidney function after living donation, Amit X. Garg, MD, PhD, Lawson Health Research Institute and London Health Sciences, London, Ontario, Canada, and colleagues analyzed data from 924 living kidney donors (mean age, 47 years; 66%, women; mean estimated glomerular filtration rate [eGFR], 100 mL/min/1.73m²) enrolled before surgery at 17 transplant centers and a sample of 396 nondonors.

After statistical weighting, the sample of nondonors increased to a pseudosample of 928, and baseline characteristics were similar to those of donors.

During a median follow-up of 7.3 years, in a weighted analysis, hypertension occurred in 17% of both donors and nondonors (weighted hazard ratio, 1.11), and the longitudinal change in mean blood pressure (BP) was similar in both groups.

After an initial drop in donors' eGFR after nephrectomy (mean, 32 mL/min/1.73m²), donors had a 1.4-mL/min/1.73m² per year smaller decline in eGFR than nondonors. However, more donors than nondonors also had an eGFR between 30 and 60 mL/min/1.73m² at least once during follow-up (47% vs 5%).

Albuminuria occurred in 15% of donors and 11% of nondonors, with a weighted between-group difference in the albumin to creatinine ratio of 1.02. No between-group differences were seen in long-term self-reported health-related quality of life, depression, or anxiety.

In an editorial, Elizabeth C. Lorenz, MD, and Wolfgang C. Winkelmayer, MD, MPH, ScD (JAMA associate editor), both of Baylor College of Medicine, Houston, wrote that while the study does provide some reassurance to living donors, the follow-up of 7.3 years might not have been long enough to identify differences in BP and albuminuria that may present later in life.

In addition, they wrote, the findings may not be generalizable because the participants were mostly White and of higher economic status, and 83% had a drug plan covering the costs of prescription medications.

Furthermore, 55% of the donors with hypertension during follow-up measured their BP at home, a finding that "suggests inadequate clinical follow-up of BP in more than half of living kidney donors."

They conclude: "These findings may not extend to donor populations who face higher lifetime risks of kidney disease and hypertension. Nor should they be applied to the increasingly medically complex donors undergoing donor nephrectomy, including donors with a baseline history of hypertension or diabetes."

Delayed Graft Function A Pitfall

Yumeng Wen, MD, PhD, Johns Hopkins School of Medicine, Baltimore, and colleagues investigated outcomes after receipt of a kidney transplant from a deceased donor who had undergone dialysis at their final hospitalization.

Study outcomes were delayed graft function (defined as receipt of dialysis by the kidney recipient a week or less after transplant), all-cause graft failure, death-censored graft failure, and death.

A total of 969 kidneys (60%) were transplanted, and the rest were discarded.

Among 514 donors who had undergone dialysis, the mean age was 33 years; 19.1% had hypertension, and 7% had diabetes. Most of the donors were on dialysis for 3 days or less (75.6%) or 4-7 days (20.2%). The researchers matched those donors with 514 individuals with the same characteristics who had not undergone dialysis.

Kidney transplants from donors who received dialysis were associated with a higher risk for delayed graft function than kidney transplants from donors who did not (59.2% vs 24.6%, adjusted odds ratio, 4.17).

In contrast, incidence rates did not significantly differ at a median follow-up of 34.1 months for all-cause graft failure (43.1 kidney transplants per 1000 person-years from donors who received dialysis vs 46.9 kidney transplants per 1000 person-years from donors who did not receive dialysis; adjusted hazard ratio [aHR], 0.90), for death-censored graft failure (22.5 vs 20.6 per 1000 person-years; aHR, 1.18), or for death (24.6 vs 30.8 per 1000 person-years; aHR, 0.76).

Editorialists Xingxing S. Cheng, MD, and Colin R. Lenihan, MD , PhD, both of Stanford University, Stanford, California, wrote, "On its face, using kidneys from donors who received dialysis prior to dying seems counterintuitive. However, kidneys have a remarkable potential for regeneration and recovery even after severe insults."

That said, they noted that delayed graft function adds significantly to both the cost of a transplant and length of the hospital stay. Because there is no reimbursement for these additional costs and kidney transplant programs are penalized for graft nonfunction (ie, the graft doesn't work at all), it is "fiscally unsustainable" for kidney transplant programs to expand their deceased donor acceptance criteria to take on these higher-risk donors.

"A meaningful increase in organ availability will likely require drastic technological or policy breakthroughs, such as xenotransplant or the removal of barriers to living donation," they wrote. "Until then, the kidney transplant community will continue to scrimp and save."

For the living kidney donation study, the Canadian Institutes of Health Research (CIHR) provided operating grant support. Astellas Pharma Canada and Novartis provided partnership funding for the CIHR-funded grant. One coauthor reported receiving industry fees.

Editorialist Winkelmayer reported receiving personal fees from Akebia, Anthos, AstraZeneca, Bayer, Boehringer Ingelheim, Cadrenal, GlaxoSmithKline, Merck, Natera, Novartis, Pharmacosmos, Unicycive, Vera, and Zydus.

The deceased donor's study was supported by numerous grants from various institutes within the US National Institutes of Health and from a Kidney Center grant at Yale University awarded to one coauthor. Wen disclosed being an employee of Genentech and holding stock and stock options in Roche at the time of the manuscript revision; other coauthors also reported fees from industry.

Editorialist Cheng reported grants from the US National Institute of Diabetes and Digestive and Kidney Diseases.

Marilynn Larkin, MA, is an award-winning medical writer and editor whose work has appeared in numerous publications, including Medscape Medical News and its sister publication MDedge, The Lancet (where she was a contributing editor), and Reuters Health.