Illustration: Chris Sharp

Last year, Richard Krafton of Andover, Massachusetts, got some very bad news. High blood pressure was destroying his kidneys, and he would need to start dialysis and join more than 67,000 Americans waiting for a transplant. His doctor estimated it could be seven years before Krafton moved up the list and found a kidney that matched his blood type and wouldn’t be rejected by his immune system.

But thanks to a collaboration of doctors and economists, including a Boston College professor of economics, Tayfun Sönmez, Krafton was on the operating table within a year, getting a kidney from a live donor, a woman he’d never met. At the same time, Krafton’s brother-in-law was in a New York City hospital donating a kidney to the cousin of that woman’s good friend. The simultaneous transplants were facilitated by the New England Program for Kidney Exchange (NEPKE), which Sönmez helped establish in the fall of 2004 at the New England Organ Bank, in Newton.

Sönmez specializes in market-mechanism design and social choice theory, branches of economics that he has also applied to studies of school choice and school assignment in the Boston public education system. In the case of kidney exchange, the process, in its simplest form, works like this: Say somebody offers a kidney to a (blood-type A) relative, but it’s discovered that the would-be donor (blood-type B) is not a match. The NEPKE database is searched and another patient-donor pair is found that has been stymied by the same incompatibility, albeit reversed.

“It’s basically a swap,” explains Sönmez, who notes that such kidney exchanges were performed before NEPKE, but were ad hoc and rare, dependent on the memory and initiative of individual clinicians. The innovation of Sönmez, working with fellow economists Alvin Roth of Harvard University and M. Utku Ünver of the University of Pittsburgh, was to vest donor altruism with a new level of efficiency, yielding a greater number of life-saving transplants.

The economists teamed with two physicians—Susan Saidman, a pathologist at Massachusetts General Hospital, and Francis Delmonico, a transplant surgeon at MGH and former president of the board of directors for the United Network for Organ Sharing (UNOS), which coordinates organ transplants for the U.S. Department of Health and Human Services. With the doctors’ input, the group’s kidney exchange simulations have been written up in both economics and medical journals over the past couple of years.

For example, in the journal Transplantation (March 2006), Sönmez and his coauthors report that in a random sample of 100 incompatible patient-donor pairs, about 50 matches were found when exchanges between two pairs were considered. The number of potential transplants climbed to 60 if doctors also considered three-way kidney exchanges. Larger exchanges provided a slightly bigger increase, but in the real world, the authors note, they would pose serious logistical challenges, since exchange trans­­plants are conventionally performed simultaneously to ensure no donor backs out. The researchers have also explored the potential ripple effects of donations made to patients waiting in the deceased-donor queue in exchange for upgrades on the list for nonmatching relatives or friends.

Both three-way and de­ceased-donor list exchanges are now arranged by NEPKE. The organization also invites so-called Good Samaritan donors willing

to give up a kidney with no particular recipient in mind. The prospect of saving more than one life by triggering an exchange “might even increase the motivation for this kind of donation,” Sönmez says.

Currently, about 35 mismatched patient-donor pairs are in NEPKE’s database. During the first six months of 2006, the system’s monthly matching resulted in five transplants, including one three-way exchange; nine more are pending. The success has caught the attention of UNOS, which earlier this year called for a national kidney exchange, citing the potential to add 2,000 additional transplants to the approximately 15,000 now performed every year.

Thorny questions remain. Should all exchanged kidneys be valued equally, for instance, no matter the age of the donated organ? And what is the optimal time to allow for a variety of patient-donor pairs to accumulate before searching for matches? Sönmez feels fortunate to be confronting such problems. “As economists, it’s not often that the tools we develop are meant to save lives,” he says.

Chris Berdik is a writer based in Boston.

Read more by Chris Berdik