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.

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  1. deriuqer says:

    The big problem is that this doesn’t decrease the probability of reneging enough. After getting a kidney people can “suddenly” change their mind, breaking the chain. I can easily picture myself having second thoughts, although maybe not acting on them. So the first donor, altruistic as he might be, he’d be reluctant to give a kidney away if the probability of the chain breaking is as high as I think it is, even right at the first link. What Roth’s example really shows is how even tiny changes in stability of the chain can work sometimes, but for this to become a meaningful contribution to the market size one needs to be enormously altruistic — a black swan of altruists.

    Looks like there is no way around fighting the stupid repugnance. Repugnance is endogenous after all. Roth’s second best solution is great, but even it has the negative externality of decreasing the incentive to push towards the first best. Why pushtowards legalizing trade if “we can build chains like these to save lives” — never mind that the chains are unstable which makes the market practically nonexistent and Roth’s solution much less relevant.

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  2. Charlottesville says:

    Sorry, that was very, very confusing. What is a “couple”? What does this have to do with organ sales?

    The way this was written it makes it sound like someone is having one kidney removed and a new one put it but that new one will be donated somewhere else one day.

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  3. Levi Funk says:

    To avoid reneging, you could require each recipient’s spouse to simultaneously donate. Even better, put the spouse under before you put the recipient under. That should ensure a long enough chain.

    Unfortunately this idea only works for those who are in a relationship or have someone close to them that is willing to give them a kidney. However, it is a wonderful way to solve the problem of being a poor match for your significant other.

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  4. Adriana says:

    A couple means a receiver with end-stage kidney disease and a healthy donor. So, A is willing to donate a kidney to B, but they are not a match. C is willing donate a kidney to D, but they are also not a match. However, A is a match to D and C is a match to B, making it possible for them to trade the organs.

    The point of the chain is that if you need a kidney, you need to have someone willing to donate a kidney even if this person is not your match. Once you get your kidney, your donor will have to donate their kidney to someone else.

    This way the money incentive to sell an organ is substituted by the incentive that your loved one will get a kidney if you decide to donate yours, even if you two are not a match.

    It’s a great idea.

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  5. kip says:

    This was an episode of Grey’s Anatomy..

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  6. Helen Rambaut says:

    Certainly an idea worth developing. I think all potential routes need to be developed to increase the supply of healthy kidneys.

    Receiving a replacement kidney is an incredible transformation from being very sick to being healthy again.

    Under a well regulated system of selecting healthy living kidney donors and committing to ther long term follow up and aftercare, I have no objection to exploring the use of the price mechanism to atttract donors.

    It’s a wonderful feeling to receive an altruistic donation but in practice I dont see why the donors should have to do it for free when at the same time as prolonging life they are significantly reducing healthcosts borne by the taxpayer.

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  7. spoon says:

    Every donor after the first altruistic donor is also an altruistic donor as they no longer have a reason to donate. The initial donor makes the donation circle a line to where the intricate loop would have eventually broken, or if it hadn’t broken the last person doesn’t need to donate.

    Presumably kidneys can’t sit around for very long at all after being donated or there would be a kidney bank funded by altruistic donors, if someone you knew then needed a kidney you could trade yours in for one better suited for them from the bank.

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  8. Mark says:

    “Every donor after the first altruistic donor is also an altruistic donor as they no longer have a reason to donate.”

    Not, they’re not. They agreed to a contract, and they’re just fulfilling their part. I think many people try follow up on their obligations even if they could get out of them without consequences. Do you not?

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