Nicola M. Parry, DVM
August 27, 2019
Deceased-donor kidneys are twice as likely to be discarded in the United States as they are in France, according to a study published online August 26 in JAMA Internal Medicine.
"The high discard rate of deceased-donor kidneys is a major concern for the US transplant field," report Olivier Aubert, MD, PhD, from the Paris Translational Research Center for Organ Transplantation, France, and colleagues.
The US kidney transplantation system still has substantial room for growth, they emphasize, by accepting more organs from deceased donors who are older and have comorbidities such as diabetes and hypertension.
"We found that the age and [Kidney Donor Risk Index (KDRI)] of US deceased donor kidneys remained stable from 2004 to 2014 in the United States, whereas the French transplant system responded to the organ shortage by accepting lower-quality kidneys, especially those from older donors."
The lack of kidneys available to meet transplantation needs is a major public health problem worldwide.
Each year in the United States, approximately 5000 patients die while waiting for a kidney transplant. Meanwhile, more than 3500 donor kidneys are discarded.
With this in mind, Aubert and colleagues performed a computer simulation-based study to investigate the hypothetical benefit of transplanting kidneys that would typically be discarded in the United States.
Using registries in the United States and France, the researchers compared data for kidney transplant and discard practices between the two countries from 2004 to 2014.
Of the 156,089 deceased-donor kidneys that were recovered during this timeframe in the United States, 128,102 were transplanted and 27,987 (17.9%) were discarded.
By contrast, 29,984 kidneys were recovered in France, of which 27,252 were transplanted and 2732 (9.1%; P < .001 vs United States) were discarded.
However, transplanted organ quality was lower in France, as indicated by a greater mean (KDRI) of transplanted kidneys compared with the United States (1.50 vs 1.23; P < .001). French donors were significantly older (50.91 vs 36.51 years; P < .001), and were significantly more likely to have had hypertension (24.76% vs 29.06%; P < .001) or have died of cerebrovascular causes (32.68% vs 54.57%; P < .001).
During the 10-year study period, KDRI steadily increased from 1.37 in 2004 to 1.74 in 2014 in France, which is consistent with more aggressive organ use. This rise predominantly reflected an increase in the mean donor age in France compared with in the United States (56.17 vs 39.08 years in 2014).
However, there was no significant change in the mean KDRI in the United States during the study period (1.30 in 2004 vs 1.32 in 2014).
The researchers estimate that 17,435 (62%) of the kidneys that were discarded in the United States during the study period would have been transplanted under the French transplant model.
According to the authors, this would have provided 132,445 more allograft life-years by 10 years posttransplantation in the United States.
"Greater acceptance of kidneys from older and comorbid deceased donors in the United States could provide major survival benefits to the population of wait-listed patients," Aubert and colleagues conclude.
In an accompanying commentary, Ryoichi Maenosono, MD, and Stefan G. Tullius, MD, PhD, both from Brigham and Women's Hospital, Harvard Medical School, Boston, Massachusetts, stress that effective organ use involves taking advantage of a less robust immune response in older recipients as well as matching the life expectancy of donor organs and recipients.
"The 'old-for-old' approach taken by Eurotransplant has been implementing those principles for almost 20 years," they write.
However, the commentators also emphasize the need to consider other important factors that invariably affect donor kidney discard rates.
These include the racial mix of the United States, with more African Americans, more donors after circulatory death, and more hepatitis C-positive donors.
Since 2014, US kidney allocation regulations have also increased the likelihood that younger recipients with a longer estimated posttransplant survival will receive a younger kidney. This leaves older recipients more likely to receive an older one, they add.
"Specifics of regulatory, financial, or medical assessments appear to be the driving force" behind the high discard rate in the United States, Maenosono and Tullius write.
Indeed, the intense regulatory monitoring of US transplant programs has led to many of them taking a risk-averse approach.
"Hospital administrators and patients alike are attracted by superficial 5-star ranking approaches that are easy to read but not necessarily reflective of the approach of individual programs aiming to provide their patients on waiting lists with the best opportunities," they write.
However, they note, the Collaborative Innovation and Improvement Network, an initiative from the United Network for Organ Sharing, aims to improve the use of high-KDPI organs.
In addition, the US Centers for Medicare and Medicaid Services is considering removing some regulations that affect the funding of transplant programs if they fail to meet expected outcomes.
"Organ transplant clinicians and program administrators need to understand that some outcome measures including KDPI, biopsies, and flow parameters may not necessarily reflect the quality of an organ or its benefit to someone in need of a transplant," Maenosono and Tullius conclude.
"[W]e should focus more on the needs of the potential recipients and less on the donor kidneys."
This study was supported in part by the French national research agency (INSERM), Fondation Bettencourt Schueller, Agence de la Biomédecine, and the Health Resources and Services Administration. One author has reported receiving investigator-initiated grants from Merck, AbbVie, and CVS Caremark to the University of Pennsylvania, and serving as associate editor for the American Journal of Kidney Diseases. Another author has reported receiving personal fees from Alexion and CSL Behring outside the submitted work. The remaining authors and commentary writers have reported no relevant financial relationships.