Challenges to building a national program
There are several notable differences between living donor kidney transplants and living donor liver transplants. For example, living donor liver transplant is a more complicated surgery and poses greater risk to the donor. According to the OPTN 2020 Annual Report, from 2015 to 2019, the rehospitalization rate for living liver donors was twice that of living kidney donors up to 6 weeks after transplant (4.7% vs. 2.4%). One year post transplant, the cumulative rehospitalization rate was 11.0% for living liver donors and 4.8% for living kidney donors.
The risk of dying because of living donation is also higher for liver donors compared to kidney donors. The National Kidney Association states that the odds of dying during kidney donation are about 3 in 100,000, while estimates for risk of death for living liver donors range from 1 in 500 to 1 in 1,000. But some of these estimates are from 10 or more years ago, and outcomes have likely improved, said Whitney Jackson, MD, medical director of living donor liver transplant at UCHealth University of Colorado Hospital, Aurora. Her program is participating in the UNOS pilot.
More recent data from OPTN provides some idea of risk: Of 3,967 liver donors who donated between March 1, 2008, to Sept. 30, 2022, three deaths were reported within 30 days of transplant. However, the causes of death were not specified and therefore may be unrelated to the surgery. By comparison, of 74,555 kidney donors during that date range, 10 deaths were reported at 30 days post surgery.
In addition to a more complex surgery, surgeons also have a smaller time window in which to transplant a liver than than they do to transplant a kidney. A kidney can remain viable in cold storage for 24-36 hours, and it can be transported via commercial airlines cross country. Livers have to be transplanted within 8-12 hours, according to the OPTN website. For living donation, the graft needs to be transplanted within about 4 hours, Dr. Samstein noted; this poses a logistical challenge for a national organ paired donation program.
“We worked around that with the idea that we would move the donor rather than the organ,” he said. The program will require a donor (and a support person) to travel to the recipient’s transplant center where the surgery will be performed. While 3 of the 15 pilot paired donation transplant centers are in New York City, the other programs are scattered across the country, meaning a donor may have to fly to a different city to undergo surgery.
Including the preoperative evaluation, meeting the surgical team, the surgery itself, and follow-up, the donor could stay for about a month. The program offers up to $10,000 of financial assistance for travel expenses (for both the donor and support person), as well as lost wages and dependent care (for the donor only). Health insurance coverage will also be provided by the pilot program, in partnership with the American Foundation for Donation and Transplant.
The program requires that transplant candidates (the recipients) be at least 12 years old, be on the waiting list for deceased liver donation at one of the pilot’s transplant centers, and have a Model for End-Stage Liver Disease (MELD) score of 25 or less. All potential donors must be 18 years or older and must undergo a medical and psychosocial evaluation. Nondirected donors can register with the program, and they will be paired with a candidate on the liver transplant waiting list at the same transplant center.
The 1-year pilot program is set to begin when the program conducts its first match run – an algorithm will help match pairs who are enrolled in the program. About five to seven enrolled pairs would be ideal for the first match run, a UNOS spokesperson said. It is possible that the 1-year pilot program could run without performing any paired transplants, but that’s unlikely if multiple pairs are enrolled in the system, the spokesperson said. At the time of this story’s publication, the one enrolled pair are a mother and daughter who are registered at the UCHealth Transplant Center in Colorado.