In February 2011 a man in California heard that the clerk at his yoga studio had given a kidney to a friend. Two days later he called his local hospital to ask how he could do the same for a stranger. His gift set off a chain of 30 transplants across the United States.
One gift, thirty kidneys
Rick Ruzzamenti was 44 and had never even given blood. On 15 August 2011 his left kidney was flown overnight from Los Angeles to Newark and transplanted into a 66-year-old man in New Jersey. That man's niece had wanted to give him her own kidney, but her blood type did not match his. So, in return for the stranger's gift, she gave her kidney to someone else, whose partner then gave to someone else again.
The chain ran for four months through 17 hospitals in 11 states, The New York Times reported in 2012. Children gave for parents, husbands for wives, sisters for brothers. Kidneys crossed the country in cooled boxes fitted with GPS trackers on commercial flights. On 20 December 2011 the last of them reached Donald Terry Jr. of Joliet, Illinois, who had spent nearly a year on dialysis and had been told he might wait five years for a kidney from a deceased donor. Sixty operations linked 30 people who gave a kidney with 30 who received one.
The chain was organised by the nonprofit National Kidney Registry. The idea that made such chains possible had been worked out, in part, by an economist.
A problem money cannot solve
Alvin Roth was born in Queens, New York, in 1951, the son of two public high school teachers. He became an expert in game theory and in what economists call matching markets: markets where prices alone cannot do the job, because you cannot simply choose what you want, you also have to be chosen. His work on the system that places new American doctors in hospital jobs made his name.
Kidneys are the starkest matching market of all. Buying and selling organs has been illegal in the United States since 1984, and in almost every country in the world. Yet many patients have a relative or friend who is willing to donate but cannot, because of an incompatible blood type or antibodies. For years those willing donors were simply turned away.
Around 1990, teaching game theory at the University of Pittsburgh, Roth began using kidneys as a classroom example of goods that could be swapped between patient and donor pairs to find better matches. In his Nobel autobiography he recalled that he did not yet imagine it would become a practical problem. Then, in 2000, the first kidney exchange in the United States took place at Rhode Island Hospital, and his class notes suddenly looked useful.
From class notes to clearinghouse
With two economists, Tayfun Sönmez and Utku Ünver, Roth designed an algorithm for organising kidney exchanges among many incompatible pairs at once, and for linking them with donors who give without a particular recipient in mind. Their paper "Kidney Exchange" appeared in 2004. They sent a draft to many transplant surgeons. One, Dr. Frank Delmonico, replied, and the economists helped him set up the New England Program for Kidney Exchange.
Early swaps were limited. Every operation in an exchange had to happen at almost the same time, so that no family gave a kidney without receiving one, which kept exchanges to three or four pairs. Roth and his colleagues worked with the transplant surgeon Dr. Michael Rees, founder of the Alliance for Paired Donation, on a bolder design: a chain started by a single altruistic donor, in which the surgeries need not happen on the same day. Each pair receives a kidney before giving one, so if the chain ever breaks, nobody is left worse off.
In July 2007 one altruistic donor started such a chain. Over eight months it produced 10 transplants at six hospitals in five states, as reported in the New England Journal of Medicine in 2009, with Roth among the authors. In 2012 Roth shared the Nobel Memorial Prize in Economic Sciences with Lloyd Shapley. The prize committee noted that increasingly complex chains of kidney donations had been adopted in a number of U.S. states.
“Kidney exchange has now helped thousands of patients with incompatible donors receive transplants of life saving compatible kidneys.”Alvin E. Roth, Nobel laureate in economic sciences, Alvin E. Roth, Biographical, NobelPrize.org, 2012
Thousands of transplants
Exchanges and chains are now a routine part of transplant medicine. In 2000 there were about 13,600 kidney transplants in the United States; by 2022 there were more than 25,000, a rise that Stanford Impact Labs attributes in part to the creative thinking of Roth and his colleagues. In January 2025 the National Kidney Registry announced that it had facilitated its 10,000th living donor kidney transplant since its first in 2008, including 1,744 in 2024 alone.
Roth, now a professor at Stanford, has kept working to make the system reach further. With Rees's alliance and other partners he is studying how a kidney from a deceased donor might start a chain of living donations, and helping doctors in India and Brazil build legal, ethical exchange programmes. At a partner institute in Ahmedabad, India, the nephrologist Vivek Kute set the goal of doubling its number of transplants in 2024, calling the alliance's expertise and software critical.
Why it matters
Kidney exchange turns a moment of heartbreak into an opportunity. A mother who cannot give to her son can still save him, by saving someone else's son. And one person willing to help a stranger, expecting nothing in return, can set off a sequence that gives dozens of people a new life.
The need is still great. More than 96,000 people in the United States were waiting for a kidney in early 2024, and a new person is added to the list every 10 minutes. Roth has said plainly that much more remains to be done. But the matching ideas he helped bring into medicine show how careful thinking, generosity and trust can work together. The next chain is being built today, one match at a time.
People in this story
Sources & further reading
- Alvin E. Roth: Biographical, NobelPrize.org
- The Prize in Economic Sciences 2012: Popular information, NobelPrize.org
- How Does Applied Economics Maximize Kidney Transplants?, Stanford Impact Labs
- 60 Lives, 30 Kidneys, All Linked (Kevin Sack, The New York Times, 2012), NBC News
- A nonsimultaneous, extended, altruistic-donor chain, New England Journal of Medicine (PubMed)
- National Kidney Registry Facilitates 10,000th Living Donor Kidney Transplant, National Kidney Registry
- Kidney paired donation, Wikipedia
Researched from the sources above and checked against them. Spotted an error? Tell us.
Tikkun olam in action. This is part of tikkun olam, the Jewish idea of repairing the world, and every one of us can add to it.
