Scientists Devise Method To Increase Kidney Transplants

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Date:     June 11, 2007

Scientists Devise Method To Increase Kidney Transplants

Science Daily — Computer scientists at Carnegie Mellon University have developed a new computerized method for matching living kidney donors with kidney disease patients that can increase the number of kidney transplants -- and save lives.

Tuomas Sandholm. (Credit: Image courtesy of Carnegie Mellon University)

This step-by-step method, or algorithm, could significantly boost the efficiency of kidney exchanges, a mechanism for matching live donors with unrelated recipients. Kidney exchanges are now considered the best chance for boosting the number of kidney transplants in the United States. More than 70,000 Americans are on the waiting list for kidney transplants and about 4,000 die waiting each year.

The matching algorithm makes it possible to create matches for three- and four-way exchanges -- that is, three or four donors matched to three or four recipients -- as well as two-way exchanges. It is the first that is scalable so it can be used for a national pool of donors and recipients, said Tuomas Sandholm, professor of computer science.

A paper detailing the algorithm, developed by Sandholm, Computer Science Professor Avrim Blum and graduate assistant David J. Abraham, will be presented Friday, June 15, at the Association for Computing Machinery's Conference on Electronic Commerce in San Diego.

The Alliance for Paired Donation, a kidney exchange program for 50 transplant centers in 15 states, began using the matching algorithm in December. The Alliance director, Dr. Michael Rees of the University of Toledo Medical Center, said it improves on previous methods both by including three- and four-way exchanges and by factoring in so-called altruistic donors -- kidney donors without a specified recipient.

For instance, in a match run in early May, the algorithm identified four potential two-way exchanges, three three-way exchanges and one four-way exchange among about 100 donor-patient pairs and seven altruistic donors. Whether any of those transplants take place will depend on factors such as final compatibility testing, Rees said. With the same set of donor-patient pairs and without altruistic donors, the matching method previously used by the Alliance would have identified only one two-way exchange, he added.

About 140 paired kidney donations have occurred in the United States since 1999, Rees said. These paired donations can happen when a friend or loved one is willing to donate a kidney to a patient but is found to be incompatible. When possible, a paired donation is then arranged, in which donor A is incompatible with recipient A, but can donate to recipient B, and donor B can donate to recipient A.

Sandholm said the number of transplants could be increased by expanded use of three-way exchanges -- donor A gives to recipient B, donor B gives to recipient C and donor C gives to recipient A -- and four-way exchanges. Numbers could also be increased by enlarging the pool of donor-patient pairs, he added.

Several regional exchanges are in operation and the possibility of a national exchange has been discussed. Rees predicted that in perhaps five years a national pool could include 3,000 donor-patient pairs and accumulate 1,000 to 1,500 pairs each year. Potentially, as many as 2,000 transplants could be performed from a pool of this size if three- and four-way exchanges are arranged, he said. But existing matching algorithms can arrange only two-way exchanges for such a large pool, and current algorithms capable of arranging three- and four-way exchanges can handle no more than 600 to 900 pairs.

"Computer memory is a limiting factor in optimizing kidney exchanges," Sandholm said, noting the large number of constraints, such as differing blood and tissue types, that must be considered. "We work around this by using incremental problem formulation," he said. That is, the algorithm devised at Carnegie Mellon doesn't consider all of the constraints at once, but formulates them in the computer's memory only as needed, enabling it to analyze up to 10,000 donor-patient pairs.

Note: This story has been adapted from a news release issued by Carnegie Mellon University.
 
http://www.sciencedaily.com/releases/2007/06/070611093956.htm

[okarol]

I have met a potential living donor who is trying to find a recipient, and she si going to be involved in one of these "paired chains" - here's a related story - Dr. Michaels Rees is putting together matches

 How to Save a Life

By Erica Kinnaird, High Point Enterprise, N.C.

Apr. 3--GREENSBORO -- Leslie Morgan -- like many others awaiting a kidney transplant -- is running out of options.

Morgan was diagnosed with Type 1 diabetes at age 18.

After her condition became worse, she needed a transplant -- especially after doctors discovered she had only one good kidney.

The good news? She got that transplant, thanks to her sister, Sammie Allred, on Oct. 18, 2000. The bad news? Her body rejected it three years later. Ever since, she's been on a grueling schedule of dialysis three times a week, 3 1/2 hours at a time.

"It's terrible," Morgan says. "You just sit there."

A person can only live on dialysis for so many years, though -- and Morgan's family, including her husband Rusty, sisters Allred and Nell Mc Coury, and brother Fred Groome, are all on a mission to find a solution.

Thanks to an innovative doctor in Ohio, a lot of patients -- including Morgan -- who are in a holding pattern on an endless transplant waiting list may finally get a real answer, a real alternative.

Dr. Michael Rees, who works at the Medical College of Ohio in Toledo, part of the University of Toledo, created the Alliance for Paired Donation in an effort to serve kidney patients through education, charitable gifts and ongoing development of paired donation technology -- meaning computer programs that help link patients in different regions of the country. The APD's goal is to combine these regional databases to form one national paired donation program.

Morgan and her family first heard about the APD after receiving a letter in the mail about paired donation. But for a while, they heard nothing more about it.

Then Mc Coury saw a program about paired donation on C-SPAN.

"I thought, 'I've got to find out about this,'" she says.

"The gist is you give to a stranger, then someone in their family gives you a kidney in return. ... We thought it was pretty cool. We had to get her on this program."

Eventually, the family found a Web site to visit, www.paireddonation.org, and they began researching the possibility.

Only one problem, though: No one in North Carolina seemed to know about the program.

Allred made inquiries, including an e-mail to the Juvenile Diabetes Research Foundation.

She was told they didn't have any information about it, but the group apparently talked about it enough to get the attention of Rees.

"I think (the JDRF) had been talking about it, and Dr. Rees tuned in," Allred says. "He approached it because he does have a (transplant) pool and he's trying to recruit states and people into it ... It's a software system."

Rees says his father, Alan Rees, developed a computer program that would help cross-match patients with donors.

The Web-based system is set up so that anyone in the world can use it.

While it's not to that state now, it could be in the future -- there's been a lot of interest on a national level. "I'm going crazy in terms of my visits," Rees says. "There is a lot of interest now -- New Jersey, New York, Alabama, Ohio, Indiana, Texas, Arkansas, Oklahoma, Louisiana and many others. ... In two years' time, I hope to do this on a national basis. But every day, I'm learning something new -- but where there's a will, there's a way. My belief is that (with the system) we will do another 1,000 to 3,000 (kidney) transplants per year 10 years from now. I think it's really going to change things."

Rees has even met with Morgan and her family.

"What he did at that meeting was explain to us how all of it works," Allred says. "He encouraged us to join the pool."

He also told the family that they might just be lucky enough to get the program in North Carolina.

"But he would bring Leslie to Ohio if she got to the point of needing a transplant before," Allred says.

Morgan and her family are hoping for a big push, though.

"The Alliance is trying to get in other states," Allred says. "That's why we have attached ourselves to this program. It needs to be in all states and doctors know that. ... Ohio, North Carolina, Texas and all the way around the United States. (Patients and donors) would be put in a major pool to combine the efforts."

So far, the government has taken some notice.

Two bills have been introduced regarding paired donation; one has passed on the federal level -- "it passed unanimously," Allred says.

The bill, "Organ Donation and Recovery Improvement Act" (h.r.3926) became a law in April 2004, and involves education and making the public aware of the need for organ donation.

Another bill, s.487, is generally the same as h.r.3926, but would make kidney paired donations legal -- and would not be considered a transfer of a human organ for valuable consideration.

"They're trying to not get a situation where people start selling body parts and using it in a bad way," Rusty Morgan says. "Because right now, Leslie could say, ?Hey, I'll give you $10,000 if you get into this pool."

"The (bill) amendment says you cannot be criminally charged for giving a kidney," Allred says.

Morgan and her family say more steps need to be taken, though, for the bill and the Alliance to work.

"Dr. Rees had the brains to develop the system," Allred says. "He created the software but he really wants to help the patients."

Therefore, the Alliance -- a nonprofit organization -- accepts donations, which are tax-deductible.

The money will help in a variety of ways to not only transplant recipients, but to donors as well.

"It's really there to help net people," Allred says. "It helps patients live healthy lives with a kidney, and it takes care of those around them. ... We want to get the word out because we don't want families to go through what we have. We're to a point where there's nothing we can do and it just gnaws at you. We know we're on the eve of something big. Something is getting ready to happen, but we've gotta push.

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Story from REDORBIT NEWS:
http://www.redorbit.com/news/display/?id=892954

Published: 2007/04/04 15:00:50 CDT