NEAD-chain idea is based on the fact that chain transplants initiated by altruistic donors need not be done simultaneously. This idea was proposed in our AJT paper.

We showed in our AER paper “Efficient Kidney Exchange: Coincidence of Wants in Markets with Compatibility-Based Preferences” that using at-most 4-way exchanges, almost all gains from kidney exchange can be exploited. Based on this, we started to implement priority mechanisms using at most 4-way kidney exchanges in NEPKE and APD (see a related news story).

We have also authored the optimization software currently used in NEPKE and APD. However, solution of this optimization problem is in general NP complete. Thus, no efficient algorithm exists to find the outcome of our mechanisms. To handle a larger program, such as a national kidney exchange program, we proposed David Abraham, Avrim Blum and Tuomas Sandholm (computer scientists at CMU who are experts of designing memory efficient algorithms) to design an algorithm to find the outcomes of our mechanisms for larger problems. They have unveiled their algorithm that solves our proposals recently in 2007.

Here is the UNOS consensus statement that I co-authored for the implementation of a national kidney paired donation program.

Here is the recent US Congress Bill that clarifies that paired kidney donations do not violate the National Organ Transplant Act.

Press coverage:

National Science Foundation web-published a story called “Kidney Exchange: A Life-Saving Application of Matching Theory” about my research with Alvin E. Roth and Tayfun Sönmez on Kidney Exchange.

Tim Harford published a story in the Financial Times on 7/14/2007 about our work.

Steven Levitt and Stephen Dubner wrote a story citing our work on their Freakonomics column in the New York Times Magazine on 7/9/2006.

An article titled "Easing the Kidney Shortage" from the Wall Street Journal (6/17/2004) describes the basics of our kidney exchange system and outlines that New England region is considering establishment of a cross-donor database and adoption of a version of our proposed mechanism to carry out kidney exchanges among transplant patient-donor pairs.

Also see another article titled "Cross-donor system planned for region's kidney patients" from the Boston Globe (6/5/2004) on the same subject.

SIAM News also published an article about our paper in their June, 2004 issue.

Our proposals on organization of kidney exchange have been finding real life applications in other transplant centers, as well:

In our JET paper “Pairwise Kidney Exchange”, besides our mechanism design approach, we propose using combinatorial optimization and graph theoretic techniques developed by Edmonds (1965) on organizing kidney exchanges. After we published ‘Pairwise Kidney Exchange’ as an NBER working paper in the summer of 2004, Johns Hopkins team published a paper in 2005 in the Journal of American Medical Association with simulations using the generalized version of Edmonds’ (1965) algorithm that we proposed in ‘Pairwise Kidney Exchange’. Consequently, Johns Hopkins University Transplant Center adopted a pairwise kidney exchange scheme based on Edmonds’ algorithm.

In our QJE paper “Kidney Exchange”, we propose the idea of a “w-chain exchange.” Non-directed donor chain exchanges are based on the same idea, and this second idea was developed by Johns Hopkins. Recently, Johns Hopkins University conducted the first 5-way non-directed donor chain exchange, in which a non-directed altruistic donor donates a kidney to the patient of the first pair, the donor of the first pair donates a kidney to the patient of the second pair, the donor of the second pair donates a kidney to the patient of the third pair, the donor of the third pair donates a kidney to the patient of the fourth pair, and finally the donor of the fourth pair donates a kidney to a waiting list patient without a donor.

On 10/23/2008, the popular TV medical drama "Grey's Anatomy" featured a 6-way simultaneous altruistic donor chain and emphasized the ethical and institutional constraints associated with the chain. Here you can read its synopsis and watch the episode.