Domino Strategy: One Kidney Transplant Sparks Two or More

BALTIMORE, July 28 -- The shortage of kidneys for transplant could be eased by the selfless kindness of living strangers if an approach called the domino strategy were adopted widely, according to researchers here.

The so-called domino paired-donation strategy allows altruistic or "non-directed living donors" -- people who offer to donate a kidney to a stranger as a selfless act -- to be sure that their gift can benefit a recipient who needs it most, Johns Hopkins researchers reported in July 29 issue of The Lancet.

At the same time, the strategy would help a second recipient find a better donor match, Robert A. Montgomery, M.D., chief of transplantation, and colleagues.

Under a simple domino transplant scenario, a donor-recipient pair such as a husband and wife with incompatible blood and HLA types is matched with a different pair in which the donor and recipient are incompatible. Then the pairs exchange donations, with the donor in pair one giving to the compatible recipient in pair two, and the donor in pair two giving to the compatible recipient in pair one.

The domino-paired strategy takes this idea one step further. When an altruistic person steps forward and offers to donate a kidney "to anyone who needs it," the organ is given to the recipient in a mismatched pair, and the donor in that pair then gives an organ that is directed to the first eligible recipient in the UNOS (United Network of Organ Sharing) match run.

Thus, a single act of donation results in two recipients getting organs that are better matched to their medical needs and therefore more likely to result in a better clinical outcome. The benefits of the first donation can be extended further by adding a third mismatched pair into the mix, the authors said.

The domino-paired system also satisfies the donor criteria currently used in various allocation systems, in which kidneys are either given to the person who might have the best clinical outcome, the person in greatest need (such as the most critically ill or financially disadvantaged), or to the patient who is the first match at the top of the UNOS transplant list.

"Implementation of domino-paired donation on a national or regional scale should improve consistency and fairness across transplant centers, but would reduce each transplant center's autonomy in making decisions about allocation of organs," the authors wrote.

"Domino-paired donation would also be affected by the same practical limitations as paired donation in terms of the logistical difficulty of arranging paired donations between diverse and distant institutions," they noted.

Johns Hopkins surgeons have performed two triple and one double domino-paired kidney transplants, each set in motion by living non-directed donors who came forth, and resulting in eight patients receiving compatible kidneys.

If conventional allocation strategies had been used, only three of the recipients would have benefited from the altruistic donations, Dr. Montgomery said.

According to UNOS, 302 non-directed kidney transplants have been performed in the United States since the first altruistic donation was accepted in 1998.

Dr. Montgomery and colleagues used a computer model to calculate the number of transplants that would have occurred had the domino-paired model been in place, and determined that 583 transplants could have been achieved.

To ensure that healthy non-directed donors are truly acting for altruistic reasons and are not under coercion, the potential donors undergo the same psychological and social evaluation that all living donors are subjected to, Dr. Montgomery said.

"In light of the crisis the transplant community continues to experience in terms of the number of available organs," he continued, "the fact that people are coming forward voluntarily to help ease this shortage should not be treated with suspicion but rather should be considered morally praiseworthy. These are good people doing good things."