San Francisco is becoming a center for kidney exchange

UCSF Medical Center, CPMC Join Forces for 18-Patient Kidney Transplant Chain

"A unique collaboration between UCSF Medical Center and Sutter Health’s California Pacific Medical Center (CPMC) resulted in what is believed to be one of the nation’s first nine-way kidney transplant chains occurring in one city over a 36-hour period.

The chain started on Thursday morning (June 4), with an altruistic patient donating a kidney as a token of gratitude for his good health. It concluded with a recipient who has been on dialysis for several years.

The surgeries involved the above donor and recipient and an additional 16 patients – eight recipients, each paired by a friend or family member. These pairs were either blood type or immunologically incompatible with each other but were compatible with other pairs in the group.
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"“This collaboration with CPMC enables us to broaden our pool of kidney transplant donors and recipients and treat them at two medical centers separated by only a few miles,” said John Roberts, MD, professor of surgery and chief of UCSF Medical Center Transplant Service. “The proximity of the hospitals means the donated kidney can be swiftly transplanted, minimizing risks to patients. This paired kidney exchange also benefits those on the transplant waiting list and moves up others who are still waiting.”

Kidney exchange in the NY Times Magazine

Kidney exchange and public relations sometimes go hand in hand, which isn't a bad thing at all, since the more people who know about kidney exchange, the more transplants will be possible. A modest 6-transplant non-directed donor chain in California has attracted a nice story in this week's NY Times Magazine: The Great American Kidney Swap by By Malia Wollan.

Here's some of what the NY Times article has to say:

"A law-abiding American in need of a kidney has two options. The first is to wait on the national list for an organ donor to die in (or near) a hospital. The second is to find a person willing to donate a kidney to you. More than half the time, such donor-and-recipient pairs are incompatible, because of differences in blood type or the presence, in the donor’s blood, of proteins that might trigger the recipient’s immune system to reject the new kidney. The genius of the computer algorithms driving the kidney chains is that they find the best medical matches — thus increasing the odds of a successful transplant — by decoupling donors from their intended recipients. In the United States, half a dozen of these software programs allow for a kind of barter market for kidneys. This summer, doctors will most likely complete the last two operations in a record-breaking 70-person chain that involved flying donated kidneys on commercial airlines to several hospitals across the country.
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"Economists call an arrangement like this a matching market. “It is not fundamental to economic theory to assume people are selfish,” Alvin E. Roth, an economist who teaches at Stanford University, told me. Roth won the Nobel Prize in economics in 2012 for his work using game theory to design matching markets, which pair unmatched things in mutually beneficial ways — students with public schools and doctors with hospitals. In such markets, money does not decide who gets what. Instead, these transactions are more akin to elaborate courtships.

"The classic example of a matching market is the college-admissions process. Every year, tens of thousands of students apply to Harvard University. But just because a student wants a spot in the freshman class and can afford tuition does not mean he gets in. Harvard must also want him to attend. In the case of kidney exchange, this matchmaking happens at a microcellular level. White blood cells contain genetic markers, proteins that help our immune systems distinguish between our bodies and foreign invaders. The more closely a transplant recipient’s genetic markers match a donor’s, the more likely the body is to adopt that foreign kidney as its own rather than attacking it."
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The average chain length for nondirected donor chains in the U.S. has lately been around 5, The latest longest chain accomplished 34 transplants (so it involved 68 people, donors and recipients).It's possible that that the number of transplants in the chain in this story was limited by the particular, proprietary commercial software that was used. One of the interesting things about kidney exchange is that most of the software is provided for free by the researchers who develop it, and is described in the open scientific literature. The  software used by the UNOS kidney paired donation pilot program is designed by Tuomas Sandholm and his colleagues at CMU, and Itai Ashlagi (at MIT until next year, when he comes to Stanford) and his colleagues have software that is very widely used by kidney exchange networks and large transplant centers, and the latest version of this software was described in January in the Proceedings of the National Academy of Science.

You can download kidney exchange software from Itai's web page: here I've copied his instructions:

Kidney exchange source code. Instructions for how to compile can be found here. An older version in c# can be found here (for both cycles and chains), which also generates patient-donor pairs as well as compatibility matrices. The software finds an allocation that maximizes the number of transplants using cycles and chains each of a different bounded length. CPLEX is needed to use.

The latest, longest kidney exchange chain, involving 68 people, 34 transplants

The National Kidney Registry has completed a new, long non-simultaneous nondirected donor chain, maybe the longest to date. Here are some stories, from the local press at some of the hospitals involved.

Kidney exchange in which Allegheny General Hospital participates enables 34 transplants
 "A Somerset County man and 33 other renal disease patients received new kidneys this year in an unprecedented national chain of organ transplants, Allegheny General Hospital announced Wednesday.
The North Side hospital is among 26 domestic transplant centers that participated in the exchange, run through March by the nonprofit National Kidney Registry. It is the largest multi-center paired kidney exchange so far in the United States, the registry said."

The final link: UW Hospital completes longest chain of kidney donations

"A Wisconsin woman received the final kidney transplant at the University of Wisconsin Hospital in March, completing the longest chain of kidney donations.

"UW Hospital is a member of the National Kidney Registry, an organization that works to match kidney donors with recipients for transplants. The registry organized the completed kidney chain, which started and ended at UW Hospital.
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"Of the 68 people in the kidney chain, 34 donors and 34 recipients, five were connected through UW Hospital, Miller said."

D.C., Md., Va. hospitals participate in largest-ever multi-hospital kidney transplant chain
"With 34 donors and 34 recipients, Chain 357, nicknamed a “chain of love,” is the country's largest-ever multi-hospital kidney transplant chain. The National Kidney Registry worked with 26 hospitals across the country to make sure every link of the chain connected.
"Since Jan. 6, the chain has bounced across the country, including stops at MedStar Georgetown Transplant Institute in Washington, D.C.; Walter Reed National Military Medical Center in Bethesda, Md.; University of Virginia Hospital in Charlottesville, Va.; and two bouts at the University of Maryland Medical Center in Baltimore, Md."