Thursday, March 19, 2009
"Pay It Forward" Transplant Strategy
In last week's New England Journal of Medicine there was a cool article by Rees et al describing a unique pair matching strategy for kidney transplants in which an ongoing chain of kidney transplantations--beginning with a single altruistic donor--has led to the successful completion of 10 kidney transplants thus far.
To explain how it works, first one needs to understand how typical pair matching programs work: say you want to donate your kidney to your brother, but the cross-match is positive. A matching program will pair you up with a compatile donor-recipient pair with the same problem. You can donate your kidney to the non-related recipient, and the recipient's relative (or friend) will donate their kidney to your brother. This works much of the time, but there are logistical difficulties in that both transplants must be performed simultaneously. If not, there is the potential for catastrophe: what if you donate your kidney first, but the other donor reneges once his family member is safely out of surgery? Not only does your brother not get the transplant, but any "bargaining power" he might have by having access to a potential donor is finished. Although it seems unusual, this has happened before.
The new strategy--which the authors term a "nonsimultaneous, extended, altruistic donor" (NEAD) chain--relies on the initiating the chain with an altruistic donor. This individual wants to donate a kidney but is not seeking anything in return. The altruistic kidney is given to a recipient who has a willing-but-non-matching donor. After receiving the altruistic kidney, the willing-but-non-matching donor donates his kidney to an unrelated recipient. This continues in a "pay-it-forward" type arrangement indefinitely. While there is still the possibility for pulling out of the deal and stopping the chain at any point, the consequences of doing so are less dire in the sense that nobody is really getting screwed by losing their donor kidney. Furthermore, in this article the first 10 individuals in the chain (which is still ongoing) have not reneged on their commitment to donate a kidney following the receipt of a transplant of their loved one.