Statistics from the US Department of Health show that some 95,000 Americans with kidney failure are waiting for a donor organ. Unfortunately, nearly 9,000 of these patients cannot get a kidney in time each year, and according to the National Kidney Foundation, 13 people die every day while waiting for a kidney transplant. Despite the tremendous and ever-increasing demand for donor kidneys (growing 8% per year), many kidneys from deceased organ donors are discarded or rejected each year after they do not pass inspection based on current medical criteria. The national discard or rejection rate for all potential donor kidneys is approximately 18%, but for acute kidney injury (AKI) kidneys, it jumps to about 30%.
The National Kidney Foundation describes AKI as a “sudden episode of kidney failure or kidney damage that happens within a few hours or a few days.” This causes waste products to build up in the blood, making it hard for kidneys to maintain the correct balance of fluids in the body. The disorder is most commonly seen in hospitalized patients whose kidneys are affected by medical and surgical stress and complications. Under current guidelines, kidneys harvested from donors that have AKI are commonly rejected, as reflected by the 30% rejection rate mentioned above. However, a recent paper in JAMA Network Open shows that transplanted kidneys from deceased donors who had AKI do not fail or get rejected after transplantation at a greater rate than noninjured kidneys from similar deceased donors.
"We estimate there may be hundreds of kidneys with AKI each year that are going unused but could be transplanted," senior author Chirag Parikh, MD, PhD, said in a press statement. "Therefore, we are urging the transplant community to bring AKI kidneys into the donor pool with more confidence," said Parikh, who is director of the nephrology division at the Johns Hopkins University School of Medicine.
An earlier study by Parikh and colleagues published in January 2019 had previously reported no significant differences in the rates of organ rejection among kidneys from deceased donors with or without AKI. This conclusion came from a review of medical records documenting approximately 2,500 kidney transplants from nearly 1,300 deceased donors of which 24% (about 600) had AKI at the time of donation. However, this suffered from the small sample size, like other studies before it.
For the latest study, published in January 2020, the researchers greatly expanded the number of transplanted kidneys analyzed to validate or refute the 2019 results. Organs from 13,444 deceased donors were transplanted into 25,323 patients in the United States between January 1, 2010 and December 31, 2013. Using a 1:1 propensity score-matched analysis, donors with and without AKI and their corresponding kidney recipients were matched, allowing for accurate comparison of characteristics including age, sex, ethnicity, AKI stage, and other medical conditions. Of the 25,323 patients, 12,810 received kidneys with AKI and 12,513 were given kidneys without any signs of acute injury that had been matched to the AKI kidneys on other criteria.
Researchers followed the transplant recipients for four to six years after their surgery and concluded that deceased donor AKI kidneys transplanted in the study period had recipient graft survival comparable to that of non-AKI kidneys and “had no association with either short-term or long-term survival of the organ, strongly supporting our idea that kidneys with AKI should be actively harvested and transplanted,” Parikh says.
According to Parikh, “Although nearly 17,500, or 85%, of the more than 20,500 available AKI kidneys were harvested over the three years, only slightly more than 12,700 were transplanted. This means almost 8,000 organs were either rejected after procurement or never obtained at all simply because the donors had acute kidney injury.”
The study concludes that the transplant community should continue to use deceased donor AKI kidneys and consider research to investigate whether currently discarded AKI kidneys from deceased donors without substantial comorbidities could be used more effectively.