Fairness and Efficiency: Designing a Better Kidney Allocation System

Each year approximately 11,000 people receive kidney transplants from deceased donors, but nearly 100,000 people are on the waiting list for a deceased donor kidney. This means that people with end-stage renal disease who desperately need a new kidney can spend years on dialysis, waiting for a transplant.

For the past seven years, the United Network for Organ Sharing (UNOS), the non-profit organization that manages the organ transplant system with the United States government, has been trying to revise its system for allocating kidneys from deceased donors to improve efficiency fairly, but so far none of the proposals have adequately addressed all aspects of the problem. After spending six years on the UNOS ethics committee, a bioethicist from the University of Chicago Medicine worked with a team to write a new proposal that could change the kidney transplant system for the better.

Lainie Friedman Ross, MD, PhD, the Carolyn and Matthew Bucksbaum Professor of Clinical Medical Ethics at the University of Chicago Medicine, said UNOS needs to address the system because the waiting list is going to keep growing. “This year we’re going to get about 11,000 kidneys from deceased donors. We’re probably going to get another 6,000 from living donors, but that’s only 17,000 kidneys and more individuals will join the list than will get off the list because demand is growing faster than supply,” she said.

The new proposal, published in the American Journal of Transplantation, uses a two-step model for allocating kidneys called “Equal Opportunity Supplemented by Fair Innings.” This system would take the pool of adult waitlist candidates and allocate kidneys based on a two-step methodology (there is a separate method for children called Share 35, which the proposal leaves as is). It was co-authored by J. Richard Thistlethwaite, Jr., MD, PhD, professor of transplant surgery at the University of Chicago Medicine; Will Parker, a medical student at the time who is now a first year resident at the University of Chicago; Robert Veatch, PhD, professor of medical ethics at the Kennedy Institute of Ethics at Georgetown University; and Sommer Gentry, a statistician from the United States Naval Academy and Johns Hopkins School of Medicine.

“We wanted our first step of fairness to say basically everyone deserves a fair shot at getting a kidney. I don’t care if you’re 20-years-old or 75-years-old, if you need a kidney you should have an equal chance of getting it,” Ross said. In the second step, kidneys from younger deceased donors would be allocated proportionally to the younger waitlist candidates.

To give an example, say that in a given year, 100,000 people were on the waiting list but only 10,000 kidneys were available. That means 10 percent of the people on the list will get a donor kidney that year.  For practical reasons, the authors showed how their system would work if donors and candidates were divided into age groups such as 18- to 34-year-olds, 35- to 49-year-olds and so on.  If 28,000 people—or 28 percent of the total waitlist—were in the 35- to 49-year-old group, then 2,800 waitlist candidates would receive kidneys under the proposed system; that’s 10 percent of that age group, keeping it in line with the percentage of the total waitlist that will receive kidneys.

That takes care of the “equal opportunity” part of the proposal, but what does “fair innings” mean? It’s a term popularized by bioethicist and philosopher John Harris that means everyone is entitled to a certain life span to have what’s considered a fair shot at life, or a fair number of innings played (Harris is British, so the innings in this case are actually a reference to cricket, not baseball). In the United States, this might mean 65-80 years for a “fair” lifespan.

In this context, Ross and her team proposed that the youngest donor kidneys should be given to the youngest waiting list candidates first. Younger kidneys generally last longer, so from a fairness standpoint it makes sense to give the youngest, healthiest kidneys to people who haven’t lived their fair number of innings yet.

Ross also uses the term “prudential lifespan equity” to describe this part of the proposal, which means that a transplant recipient should get an organ from a donor roughly the same age, because that’s what they would have naturally. This method is also more efficient, because it matches the youngest kidneys that will last the longest with younger recipients who have a longer life ahead of them.

Together, the two parts of this proposal satisfy a rule in the 1984 National Organ Transplantation Act that says that any changes to the kidney allocation system must balance efficiency, i.e. getting the most years of life from a deceased donor organ, with equity, or giving everyone a fair chance at getting an organ regardless of age or health status.

“From an efficiency perspective you want to give kidneys to the youngest people, but there’s a fairness component which says that everybody who is sick wants and needs a kidney,” Ross said.  “Rarely do people in kidney failure prefer to be on dialysis indefinitely, and nobody thinks that 50 years is a full life. So that’s what you have to balance — equity and efficiency.”

UNOS has been evaluating another alternative to the current system called the 20/80 model for the past two years. This model would allocate the top 20 percent of donor kidneys, determined mainly by age and lack of co-morbidities of the donor, to the top 20 percent of candidates, in this case young healthy individuals without co-morbidities. The remaining 80 percent would be matched by age, plus or minus 15 years. But the US Department of Health and Human Services Office of Civil Rights has said the proposed age-matching system was arbitrary and would not meet the requirements of the Age Discrimination Act of 1975.

Ross said her team’s proposal would even out the numbers of donor kidneys given to each age group to maintain a fair distribution. They believe it will meet the standards of the Office of Civil Rights because it ensures equal opportunity, regardless of age.

“Everybody should have a fair chance at getting a kidney. We’re not looking to give more kidneys to young people or old people, because we don’t think that’s fair,” she said. “Everyone who’s sick thinks that they should have a chance of being made well, and we agree. You don’t care if you’re 20, 40, 50 or 70, you still value your life.”

Ross and her team have presented their findings to the UNOS ethics committee, and will meet with the UNOS kidney transplantation committee later this summer. If UNOS decides to further evaluate this model as a basis for a new kidney allocation system, Ross said, it will require additional work.   “We know that the next steps will involve a lot of modeling and fine-tuning allocation criteria,” she said.  “We hope that UNOS will take this on, because we share the same goal: to improve the current system fairly.”

Ross LF, Parker W, Veatch RM, Gentry SE, & Thistlethwaite JR Jr (2012). Equal Opportunity Supplemented by Fair Innings: Equity and Efficiency in Allocating Deceased Donor Kidneys. American journal of transplantation : official journal of the American Society of Transplantation and the American Society of Transplant Surgeons PMID: 22703559

About Matt Wood (531 Articles)
Matt Wood is a senior science writer and manager of communications at the University of Chicago Medicine & Biological Sciences Division.
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