Studies Indicate that Biopsies Do Not Determine Suitability of Organs for Transplantation

Deceased-donor kidneys retrieved for transplantation are increasingly being discarded, and the most common reason given for discarding the kidneys is biopsy results.

Two new studies published in the Clinical Journal of the American Society of Nephrology suggest that procurement biopsies are not predictive of posttransplant outcomes and may only serve to dissuade the use of kidneys that are otherwise suitable for transplant. The findings suggest that other methods are needed when weighing whether to transplant a deceased-donor kidney.

Biopsy-reported acute kidney injury and allograft outcomes

Given ever-increasing numbers of patients with end stage renal disease, the medical community has pushed to expand the deceased-donor organ supply. Unfortunately, a clear and consistent balance between organ acceptance and discard after procurement has been difficult to achieve given a lack of precise tools to assess donor kidney quality and prognosis.

“Kidney researchers are investigating newer, non-invasive tools to assess kidney tissue injury, but we need to fully understand the utility and limitations of our current gold-standard, invasive assessment tool–kidney biopsy,” said Isaac Hall, MD, MS, of Yale University and the Veterans Affairs Medical Center. He and Chirag Parikh, MD, PhD, led a team that looked for associations between biopsy-reported acute kidney injury at the time of organ procurement with subsequent kidney transplant outcomes.

“We were hoping to expand our knowledge about these associations and explain inconsistent findings in the medical literature by performing the largest multicenter study of its kind to date,” Hall said.

Between March 2010 and April 2012, the researchers biopsied 651 kidneys (taken from 369 donors through four organ procurement organizations) that were later transplanted into recipients. The team found that biopsy-reported kidney injury was modestly associated with a delay in organ function in the first week after transplantation, but only for a subgroup of donor kidneys already known to be at high risk for this early outcome. The investigators also found that donor kidney biopsies frequently underreported acute kidney injury with substantial variability.

“Biopsies are listed as the primary reasons for discarding deceased-donor kidneys; however, as they currently relate to reported acute kidney injury, they provide little utility for determining the overall risk of delayed organ function or even premature organ failure,” Parikh said.

The authors noted that additional studies are needed to determine how biopsies should affect patterns of organ acceptance or rejection and whether newer methods might be better.

Biopsies of discarded kidneys vs. matched transplanted kidneys

In another study, Bertram Kasiske, MD, of the Scientific Registry of Transplant Recipients and Hennepin County (MN) Medical Center, and his colleagues compared the results of biopsies from kidneys that were discarded with the results of biopsies from comparable kidneys that were successfully transplanted.

The researchers compared biopsies of both kidneys from the same donor, when one kidney was transplanted and the other was discarded. The analysis included biopsy reports from 83 kidneys discarded in 2010 due to biopsy findings, 83 contralateral transplanted kidneys from the same donor, and 83 deceased donors randomly matched to cases by donor risk profile.

“We found that there was a large degree of overlap between the results of biopsies between kidneys discarded and kidneys transplanted, which raised the question of whether these biopsies can predict outcomes accurately enough to use in the decision to discard or transplant a kidney,” Kasiske said. Also, a comparison of two biopsies from the same kidney often demonstrated significant differences.

The researchers also found that the quality of the biopsies used in acceptance decisions was low. The percentage of glomeruli that were scarred was most often used to decide whether kidneys were discarded or transplanted; however, this value was highly variable, even in biopsies from the same kidney.

Graft survival at 1 year was 80 percent for kidneys contralateral to discarded kidneys. This compares with graft survival of 92 percent among all deceased-donor transplants in the Scientific Registry of Transplant Recipients. Therefore, many patients may have benefited from kidneys that were discarded. “If the discarded kidneys had been transplanted with the same graft survival as the transplanted kidneys from the opposite side, many patients may have benefited,” Kasiske said. The results question whether routine procurement biopsies result in discarding kidneys that could be acceptable for many of the patients who die waiting for a kidney transplant.

“A reasonable conclusion from this and other studies is that the widespread practice of routinely obtaining biopsies to aid in deciding to accept or reject a kidney for transplantation should be abandoned, as has been successfully done in Europe,” Kasiske said. “If abandoning this practice is not acceptable in the U.S., then perhaps additional studies could be designed to more precisely determine the benefits and harms of procurement biopsies.”

“Both of these studies highlight the limitations of using biopsy results as the sole criterion for turning down donor kidneys,” stated Sayeed Khan Malek, MD, of Brigham and Women’s Hospital in an editorial accompanying the two articles. He also expressed concern that because of the intense scrutiny and regulatory oversight of posttransplant outcomes, some low performing centers adopt a risk-averse strategy and refuse donor kidneys presumed to be of high risk owing to poor biopsy findings.

Malek noted that when biopsy findings are consistent with the clinical evaluation of the donor, they are useful in determining a kidney’s suitability for transplantation. “However, biopsy findings when considered in isolation are of limited value and should be interpreted with caution when making the decision to turn down a potentially transplantable kidney,” he wrote.