Transplant candidates may wait longer for available kidneys

September 9, 2004

Researchers from the University of Chicago and Stanford University found that one of the new programs to increase the number of kidneys available for transplantation has disadvantages for candidates with blood type O who are waiting for an organ from a deceased donor. The researchers’ findings appear in the Sept. 15, 2004, issue of Transplantation.

Through a process called list-paired exchange, a person waiting for a kidney transplant gets a higher priority on the wait list for an organ from a deceased donor when a relative makes a living donation to another waiting recipient. The living donor is not able to donate to his or her relative, usually because of blood type incompatibilities, so the willing donor gives his or her kidney to an unknown person on the wait list.

The researchers argue that list-paired exchanges are unethical because they harm an already vulnerable population. The majority of candidates waiting for kidneys have blood type O. They have the longest wait times. Where list-paired exchanges are permitted, the researchers show, wait-list candidates of blood type O are forced to wait even longer for an available deceased donor kidney.

According to the Organ Procurement and Transplantation Network, more than 30,000 people with blood type O in the United States are on the kidney wait list as of July 2004. That’s the largest number of candidates compared to the other blood types (A, B and AB). Individuals of all blood types can receive an organ of blood type O, but those with blood type O can only receive a donation from another individual of blood type O.

“Those who are already worst off – have the longest waiting times – are being asked to wait even longer in order that overall more people are getting organs,” said corresponding author Lainie Ross, M.D., Ph.D., associate professor of pediatrics and assistant director of the MacLean Center for Clinical Medical Ethics at the University of Chicago.

“The positive side of list-paired exchanges is that we are going to get more organs into the system, and anything to increase the supply is great,” Ross said. “But is it OK to increase the supply of organs if it harms a particular group of people? Justice requires that any new policies that are going to improve the well-being of the community also must benefit those who are worst off.”

The United Network of Organ Sharing (UNOS) Region 1, which includes Connecticut, Maine, Massachusetts, New Hampshire and Rhode Island, approved list-paired exchanges in February 2001.

Ross and her colleague noted a 2003 report from Region 1. In that report, all of the eight paired recipients had blood type O, but only one donor did. This means that seven individuals in Region 1 received a deceased donor kidney of blood type O ahead of those on the wait list who did not have an available living donor. The researchers said the data confirm their concern that individuals with blood type O on the wait list will be made worst off by a list-paired exchange program that permits people with incompatible blood types to participate.

In 2002, nearly 2,000 blood type O candidates died while waiting for a kidney from a deceased donor. The researchers calculated that if list-paired exchanges were adopted nationally, it could result in an average increased wait time of seven days for blood type O candidates. This translates into an additional 15 deaths per year. Since kidneys are distributed regionally, it could result in even longer wait times in some areas, the researchers note.

Ross and her colleague do not want to prohibit all list-paired exchanges. They propose limiting list-paired exchanges to pairs who are blood type compatible. They propose prohibiting only those list-paired exchanges that are blood type incompatible when the intended recipient has blood type O.

“We need restrictions for list-paired exchanges to make them a moral option,” Ross said.

The other author of the study is Stefanos Zenios, Ph.D., associate professor of operations, information and technology at Stanford University’s graduate school of business.

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