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Turning One Kidney Into Ten


Economist Al Roth has an interesting blog post that describes how one altruistic kidney donor saved 10 lives. Here’s how it worked.
One of the things Roth has been working on, given the repugnance many noneconomists feel about paying for organs, is creating chains of organ donations. Many people who need kidney transplants have a donor who is willing to donate one, but who is not a good match for the recipient.
If you can find another couple in the same situation, it just may be the case that the two donors match the recipients in the other couple. While it is illegal to sell kidneys, it is not illegal to trade them. The catch is that the surgeries need to be done simultaneously, for fear that the couple that receives the kidney from the other pair might renege on their promise to provide the reciprocal donor kidney.
The worst part of it is that the couple that gave up the kidney now no longer has a kidney to give, meaning that they cannot be part of any future swap.
In principle, there can be long chains of such donations, but having to do the surgeries all at once gets in the way. Hospitals just can’t handle large numbers of transplants all being done at once.
That’s where an altruistic donor, who isn’t asking for a kidney back in return, becomes a critical link. If you start a chain with the altruist, then the need for the surgeries to be simultaneous is not as great. The altruist gives a kidney to a recipient. The surgery is performed. Then the donor from the couple that got the first kidney, at some other date, gives away his or her kidney to the next recipient. Because there is always one “extra” kidney in the chain, when the chain finally stops, there is no couple that has given a kidney but not received one.
Consequently, the surgeries can be done over time, rather than all at once. Eventually, one of the donors might back out, or no more matches can be made, and then the chain will come to an end.
No matter when or how it ends, the key is that there is no couple who has donated a kidney but not
gotten one back in return. So every couple still has a kidney to trade as part of some future chain.
And that is how one altruistic kidney donor, with the help of clever market designers, managed to help save 10 lives.