Did you know that there is a country in which kidneys can be legally bought and sold? That country is Iran, and there are actually two models for payment. In one part of the country, donors receive a flat fee, and in the other part of the country prices are negotiated.

 

This point was actually an aside in John Dickerson’s talk on algorithms for kidney swapping at Data Science DC Dec. 13, 2016, in Washington DC. Dickerson, a member of the University of Maryland’s Computer Science Dept., focused on non-monetary mechanisms for kidney exchange.

 

In most countries, a person with renal failure can get a kidney in one of two ways:

1. By making it through the qualification and waitlist process to obtain a kidney from the “deceased donors list.”

2. By obtaining a kidney from a friend, relative, or other personally-arranged contact.

 

Unfortunately, demand far outstrips supply for option 1. And in option 2, the probability is low that a willing donor’s kidney will be compatible for the recipient. Let’s say that patients A and B have identified willing donors 1 and 2 and neither of the matches is compatible, BUT A is compatible with 2 and B with 1. A simultaneous donation could then be arranged 1 > B and 2 > A.

 

Another approach starts with an altruistic donation – one not tied in advance to a particular recipient. The recipient of that donation is then selected from among donors who have arranged their own willing donor. That willing donor then donates to a different waiting recipient, also selected from among those who have identified a willing donor, and so on.

 

Both these approaches can be depicted in a network graph, and that graph can then be used in optimization algorithms to substantially increase the number of donations, compared to those that take place in an ad-hoc, more local environment.

 

One big obstacle remains. Due to the low probabiity of matches, for this system to work well a large, hence widespread, pool of willing donors is needed. However, hospitals and donation centers are reluctant to turn their donors over to a pool outside their control, preferring to keep matters “in house.”

 

Dickerson’s excellent talk is worth a look – get an overview of the algorithms that underlie this new approach that has the potential to save many lives.