Prolonged cold ischemia time (CIT) in live donor kidneys does not worsen transplant outcomes, research shows. The finding could set the stage for more transplants involving kidney-paired donations.

The study showed that CIT as long as eight hours does not compromise renal function, raise rates of acute rejection, or diminish long-term allograft survival following transplan-tation. “One of the biggest barriers to paired donation on a national scale is the logistics of matching donor/recipient pairs across large distances,” said principal investigator Dorry L. Segev, MD, director of clinical research in the Division of Transplant Surgery at Johns Hopkins University in Baltimore, where he also is assistant professor of surgery.

“Traditionally, donors would be asked to travel to the recipient center, but this separates donors from their loved ones at a critical time. Shipping organs is one way to address these logistical issues, and a prospective demonstration of our conclusions would greatly facilitate matching on a large scale.”

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In paired donations, two donor-recipient pairs agree to swap donors to circumvent tissue incompatibility. The four transplant operations typically occur at the same center. Transportation of live-donor kidneys to recipient centers after simultaneous donor nephrectomies, according to the researchers, has been challenged on the belief it would diminish the benefits of live donation, namely a short CIT. “This argument is based on the assumption that increased CIT has the same impact on kidneys from both deceased and live donors,” they stated.

The investigators added, however, that deceased donor organs transported through regional and national sharing programs are subjected to injury associated with brain death and, in some circumstances, prolonged warm ischemia. Thus, the effect of CIT cannot be compared directly with live donor transplantation.

Using data from the United Network for Organ Sharing/Organ Procurement and Transplantation Network, the investigators studied 38,467 patients who received live donor kidneys. They divided the pa-tients into groups based on the number of hours of allograft CIT: 0-2 (the reference group), 2-4, 4-6, and 6-8 hours.

A previous study, which was published in the Journal of the American Medical Association (2005;294:1655-1663), found that with local paired kidney donation programs, transplants took place at the same center, so CIT was limited to less than two hours.

Although the rate of delayed graft function increased slightly with increasing CIT, serum creatinine values one year after transplantation were similar across CIT groups (1.4, 1.4, 1.4, and 1.5 mg/dL, respectively), according to a report in the American Journal of Transplantation (2007;7:99-107). The adjusted probabilities of acute rejection at one year were 26.5%, 20.5%, 18.9%, and 27.9%, respectively. The acute rejection rates in the 2-4 and 4-6 hour groups were significantly lower than that of the 0-2 hour group. Overall 10-year allograft survival was similar across CIT groups (56.4%, 55.5%, 53.7%, and 55.6%, respectively).
“I would predict that, based on our results, UNOS will allow transplant centers the option of shipping organs when a long-distance paired donation is arranged,” Dr. Segev said.
According to the researchers, eight hours would not be enough time to allow transport of organs across all possible distances that would be expected between donor and recipient transplant centers in a national paired donation program. A previous study, however, showed that fewer than 3% of pairs would need to travel outside of their UNOS-defined region to optimize the number of matches in a national program.