Many in need of a kidney transplant die before they ever get to the top of the queue waiting for transplants. The problem would not exist if each person in need had a family member willing to donate who was a good tissue match. But that is not true. But what is true is that for each person in need of a transplant there are many in the general population who are good matches.
The first impulse of a typical economist is to say that the shortage only exists because we don’t allow for a market in kidneys — donors can’t sell their kidneys. We allow altruistic donations from live donors, but there are not enough altruists.
Economists like Al Roth have thought seriously about this problem. Roth’s expertise is in matching problems (think, marriage partners) and he’s applied that to kidneys. The basic idea is to take the family members whose tissue was tested for a match to a relative with failing kidneys and see if it is a good match to a non-member in the queue. The trick is group of surgeries so that for each donor, his or her family member gets a donated kidney.
Roth reports on a recent chain of surgeries that resulted in ten transplants and began with an altruistic donor:
There’s a simple economic idea at work here. Mostly in kidney exchanges, all the surgeries are done simultaneously. The reason is that if two patient-donor pairs are exchanging kidneys, and if one pair were to donate a kidney to the other first, and the other were subsequently unable or unwilling to reciprocate, the pair that donated the kidney would be severely harmed; not only wouldn’t they get the kidney they had been counting on, but they would have donated their donor’s kidney and thus be unable to participate in a future exchange. But if there is an altruistic donor who doesn’t have a specific patient in mind, and if he or she gives to a patient-donor pair, and they can’t subsequently continue the chain, that is a loss, but no one is irreparably harmed. So, when chains begin with an undirected donor, they don’t have to be simultaneous, since the costs of a breach are less.
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