For patients on the waiting list for kidney transplants, there are few certainties other than the fact that transplant is better than dialysis and a living donor is better than a deceased one.
Kidney swapping—or paired donation—is one option that is helping more patients get transplants from living donors.
In a two-way kidney swap, patient A is incompatible with donor A—because of blood type and/or human leukocyte antigen (HLA) profile—and patient B is incompatible with donor B. However, donor A is a match for recipient B and vice versa. In a four-way surgery session, kidneys are removed from donors A and B and transplanted into their compatible recipients.
“The kidney swap is part of a broader, more comprehensive program for incompatible transplants, where people have live donors but are incompatible with them,” said Dr. Lloyd Ratner, who has performed several such procedures.
In 2001, surgeons at Johns Hopkins University in Baltimore performed the first paired kidney exchange in the United States. In 2003, a larger team at Hopkins performed the world's first three-way kidney swap. To date, 35 patients have received kidney transplants through such exchanges at Hopkins, said Robert A. Montgomery, Ph.D., who led those teams.
It's estimated that more than 6,000 people with willing live donors are still waiting for a kidney transplant because they are incompatible. Kidney swapping allows patients to circumvent the waiting list for a cadaveric kidney, thus shortening time on dialysis. People on dialysis live half as long, on average, as do those who receive transplants, said Dr. Montgomery, director of the incompatible kidney transplant program at Johns Hopkins University.
Dr. Ratner agreed. “The longer you've been on dialysis, your outcome is still worse than people who have been on it for shorter periods of time.” The director of the renal transplant program at New York-Presbyterian Hospital in New York City noted, “If you get a kidney from a deceased donor, there's a 50–50 chance that the kidney will last for 10 years or more. If you get a kidney from a live donor, there's a 50–50 chance that the kidney will last for 20 years or more. … If someone happens to have a perfectly matched brother or sister, there's a 50–50 chance that the kidney will last for over 30 years or more,” said Dr. Ratner.