National Kidney Registry’s Donor Chain Model Effective in Finding Donor Matches

Kendall Powell
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Three years ago, Garet Hil’s daughter’s kidneys failed, and he and his family entered a desperate race to find a living donor for her, including asking 100 family and friends to be tested and entering into every paired organ exchange program that existed in the United States. After several months of angst, they found that Hil’s 23-year-old nephew was a compatible match.

“We dodged the bullet, but it showed me that the United States needs a system to get all incompatible pairs into the database,” to facilitate as many matches between living donors and recipients as possible, Hil said. So he founded the National Kidney Registry, applying his business management savvy as a software executive to see if he could create a more efficient system for matching incompatible pairs through kidney donor chains.

The National Kidney Registry (NKR) is a 501c3 nonprofit organization that has facilitated more than 200 transplants in a little less than three years. It works with 50 transplant centers around the country. It is on target to complete 153 transplants this year and projects completing 350 in 2011, which represents about 5 percent of the total living donor transplants performed each year.

Hil explained why the donor chain model that NKR uses is more powerful for finding matches than traditional paired exchange programs. The standard chain starts with the donation of a kidney from a “Good Samaritan” donor, who is unrelated to any of the recipients. Then, matches are made between this donor and all the incompatible pairs that can find a better match within the registry participants. The last kidney in the chain—the one from a donor whose recipient has received someone else’s kidney, but whose donor kidney does not match anyone in the registry currently—then goes to someone matched from the United Network for Organ Sharing waiting list for deceased kidneys.

Gabriel Danovitch, medical director for the Kidney and Pancreas Transplant Program of the University of California, Los Angeles, has called the kidney transplant chains facilitated by the NKR “the most exciting clinical event I’ve seen in my recent career.”

In traditional paired exchange programs, the incompatible pairs have to find another incompatible pair with whom they match exactly. In the NKR model, everyone is dumped into the pool of donors and recipients in an effort to find as many compatible matches as possible. The longer the chain, the better—to date, the NKR’s longest chain involved 22 transplants—and the more quickly a chain can be ended to the waiting list, the better. So-called bridge donors, those at the end of a chain waiting to donate that “leftover” kidney, can understandably fall through, either medically or practically, if too much time passes.

In a review of 100 bridge donors, only six have resulted in broken chains. “I believe we can get this to zero eventually,” said Hil, noting that the transplant centers are getting better at identifying someone who fits the profile of a bridge donor who must wait for a time, and that matching speed can be improved. He also noted that the NKR and the transplant centers are getting better at figuring out how to coordinate larger clusters, like handling 12 simultaneous transplants in one or two days across the country to ensure that chains stay together.

In 2010, the NKR’s average wait time for a recipient to find a match and receive a transplant was eight months, compared with the industry average of more than six years. “That’s good, but not good enough,” said Hil, noting that undergoing dialysis for more than six months lowers a recipient’s chances of a successful transplant.

The NKR has also begun a CHIP program to benefit patients without donors who either are children or have a panel reactive antibody score greater than 50 percent, which indicates they are at a high risk of rejection and harder to match. Participating transplant centers can nominate these patients to receive the “leftover” kidney at the end of a chain.

Hil believes that improved donor support has been a key to the NKR’s success, including providing donor insurance for downstream complications for every “Good Samaritan” donor who starts a chain. In addition, he said, donors must be reimbursed for travel, lodging, and lost wages when possible and hospitals must stop accidentally billing donors—an error that causes donors major distress.

The entrance of more compatible donor pairs into the registry would be a win-win situation for everyone involved, Hil said. Say there is a husband-and-wife compatible pair, but he’s 10 years older than she is, and perhaps they do not have a good HLA match. Given that HLA compatibility does matter to long-term graft survival, this woman may be better off finding an unrelated, better-matched donor based on HLA, age, and weight. Also, entering this pair into the registry pool can facilitate between one and six additional transplants.

“This could cause the whole living donor transplant industry to change,” said Hil. “Currently, about 6000 living donor transplants are performed each year. By converting individual pairs into chains, we could be getting 2000–3000 more.”