The ‘Domino Chains’ Transforming Kidney Donation

Mark Scotch, then 64, met Hugh Smith, 56, in a Louisiana bar in 2020. Smith shared that he spent 10 hours a night on dialysis, needing a kidney transplant. Scotch immediately offered one of his own kidneys.

Scotch's sister-in-law had donated a kidney before, so he knew it was possible to live with one. He and his wife, Lynn, had lost their first son at 15 months and regretted not donating his organs. Meeting Smith felt like a second chance to help.

Scotch planned to cycle from his home in Wisconsin to Louisiana to donate. But he learned about a "voucher" scheme. He could donate to someone closer to home. This would move Smith to the top of the waitlist in his area. This option meant Scotch could get post-op care locally. It also ensured both he and Smith would get the best possible match.

Scotch donated his kidney to a stranger in late 2020. Five months later, Smith received his own transplant from another donor.

The Scotches are now strong advocates for living donation. Lynn later donated a kidney, and Mark donated part of his liver. Before meeting Smith, they thought only deceased donors filled the need. Mark said, "We never knew there was such a need."

The Need for Kidney Transplants

More than 90,000 people in the U.S. are waiting for a transplant. Every day, 12 to 17 people die while waiting. Many other countries face similar shortages. Kidney disease is a top 10 cause of death worldwide.

Many patients ask family or friends to donate. But often, medical or psychological issues prevent these donations. Donating to a stranger is rare, with only about 500 such donations in the U.S. each year. Most countries do not allow it due to risks to the healthy donor. Even with a willing donor, compatibility is not guaranteed. About one-third of potential donors are incompatible with their intended recipients.

Dr. Mike Rees, a transplant surgeon at the University of Toledo Medical Center, said that for a long time, incompatible pairs were simply turned away. In the early 2000s, Rees and others worked to change this. They developed "paired donation." Algorithms match incompatible donor-recipient pairs. For example, a wife incompatible with her husband could donate to another patient. That patient's loved one would then donate to her husband. This method allows 20% to 30% more transplants.

In 2006, non-directed donors (those willing to give to a stranger) joined the system. This started "domino chains." Initially, all operations had to happen on the same day. This was to prevent someone from backing out and breaking the chain. But this limited the number of transplants. A chain of three transplants needed six operating teams available at the same time and nearby.

Innovations in Kidney Exchange

Economist Alvin Roth, an expert in market design, helped create the New England Program for Kidney Exchange. This computerized system matches recipients with compatible living donors. Roth won a Nobel Prize in Economics in 2012 for his work on kidney exchange.

In 2007, Roth, Rees, and others created the first non-simultaneous, extended altruistic donor chain. In this model, surgeries do not need to happen at the same time. Each pair receives a kidney before they donate one. This offers security because if a chain breaks, the pair can still donate later.

Rees, who founded the Alliance for Paired Kidney Donation, admitted this model required trust. He worried someone might not uphold their end. But the first attempt worked, with all 10 transplants completed. After three years, the chain continued, enabling 16 more transplants. Many non-simultaneous chains have followed. Rees now believes the success makes sense. Donors are already generous people. After seeing their loved one transformed by a new kidney, they are unlikely to cheat another family.

The National Kidney Registry, a U.S. organization, created its standard voucher program in 2014. This is the scheme Smith and Scotch used. The non-simultaneous chains helped build trust in the system, making the voucher idea viable.

Samantha Hil, vice president of marketing at the National Kidney Registry and a transplant recipient, said access to a national donor pool leads to better matches. This means transplanted kidneys last longer and may need less immunosuppressive medication. Donors can also schedule surgery at a convenient time. This is helpful for donors who also care for the recipient. "This way, the donor can heal before they have to care for the recipient’s recovery," Hil said.

Researchers, including Roth, are exploring new ways to expand access. This includes using deceased donations to start chains in the U.S. and expanding exchanges in Brazil and India.

Jaya Jairam, a kidney recipient and project director at India’s MOHAN Foundation, supports expanding kidney exchange in India. She noted that kidney failure is common there, and deceased donor organs are scarce. However, strong ethical safeguards are crucial to protect donor welfare. Independent donor advocates could ensure donor interests are protected. Cultural context is also important. In India, families often make donation decisions, so women and young people might face pressure to donate.

Encouraging More Donations

Donor welfare and autonomy are key concerns for any organ donation program. But some argue that being too cautious harms those waiting for transplants. In the U.S., only about 2% of willing donors actually donate. Rees believes transplant professionals in the U.S. are too conservative. He said, "Of course we never want to coerce anybody, we shouldn’t take advantage of anybody, but I think there are a lot of people who don’t know this is an option."

Rees has seen many stories of people donating to strangers. Many say it was one of the best parts of their lives. He believes more people should have this opportunity, while ensuring no coercion.

Many agree. The proposed End Kidney Deaths Act in the U.S. would offer a $50,000 refundable tax credit to those who donate a kidney to a stranger. Supporters say this would remove financial barriers like lost income during recovery. It would also save billions spent on dialysis.

Another barrier is a lack of awareness. Hil noted that most people do not know they can donate while alive. Mark Scotch is working to change this through his Organ Trail. He has cycled over 12,000 miles and given more than 300 interviews. At 70, he shows that healthy donors can remain fit.

For people like the Scotches, donating an organ is a powerful way to make a difference. Lynn said, "What else can you do for another person that has such a significant impact on their life, and the lives of their family members, with so little impact on the donor? We haven’t found anything."