Mix, Match, and Switch
Kidney exchanges between strangers are helping to ease the organ shortage and could save thousands of lives
At 12:45, Montgomery has Shane Balhatchet's kidney in his hands, preparing to implant it into Adamson. At 1:30, Keith Melancon, another surgeon, is holding Williams's kidney, getting it ready for Shane's wife. "This looks good. The arteries look nice and healthy," says Melancon. By 4 p.m., both kidneys have been sewn into their new homes, are flushing pink as blood flows into them, and have begun doing what kidneys do best-making urine-something that Adamson's and Melanie Balhatchet's kidneys haven't done for years.
The math of making matches gets better as the pool of donors and incompatible recipients gets larger. Hopkins has perhaps 75 such pairs in its pool at any one time, and by mixing them around it might be able to find good matches for about 40 percent of them. Increase the pool to 250 pairs, and the rate climbs to 50 percent, according to theoretical models developed by Sommer Gentry, a mathematician at the U.S. Naval Academy in Annapolis, and her husband, Dorry Segev, a transplant surgeon at Hopkins. At 5,000 pairs, the match rate hits about 55 percent. "It just gets better because there are more possible combinations," says Segev.
The most combinations would be possible in a national system, of course. It could be optimized to produce the highest number of tissue matches, closest ages between donors and recipients, and the least amount of travel time for all involved.
But there is no national matching system. And one reason is a phrase in a 1984 law, the National Organ Transplant Act, which says that exchanging organs for "valuable consideration" is a criminal act. The intent was to prohibit the sale of body parts. "Some people worry that the promise to donate in return for another organ fits that 'valuable' category," says Lawrence, "so we need that cleared up." Earlier this year, Democratic Sen. Carl Levin of Michigan introduced a bill to eliminate that murk. "It doesn't remove or alter any current provision" from the law, Levin says. It simply adds a line "which states that paired donations do not violate it." The UNOS proposal letting the federally funded agency utilize its waiting lists, its data on donors and recipients, and its computers to take kidney swaps national can't kick in unless Levin's legislation passes.
David Goldfarb is already moving to create a bigger pool without government help. "People are getting sick and dying while waiting," says Goldfarb, the head of kidney transplants at the Cleveland Clinic. "But we're not the federal government. We're the private sector, and we can try and do this without federal resources." Enter the Paired Donation Network, which has grown out of an Ohio group that started four years ago with eight hospitals, including Goldfarb's. This year it's expanding to 18 states and more than 100 hospitals. "We have multiple institutions sharing data, covering a wider area. We've done calculations that show if we draw donors and recipients from a pool of 30 million people, we'll get the best matches," says Goldfarb. "Plus, if you have lots of hospitals, you have hospitals closer to the patients." So far, hospitals in this group have done 18 transplants through pairing. Another consortium, the New England Paired Kidney Exchange Program, has 14 hospitals, which have done 17 transplants.
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