Organization of Live Donor Kidney Exchanges
Adoption of Children
(See this document for Media Coverage
of my research)
Organization of Live Donor Kidney
Exchanges (aka Kidney Paired Donation)
Here are some of my lecture notes explaining the concept of kidney exchange.
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.
The earlier achievements are surveyed in my survey paper with Tayfun Sonmez.
Here is the link to the presentation speech of Professor Torsten Persson of Royal Swedish Academy of Sciences at the 2012 Nobel Prize Ceremony regarding
the role of my research on kidney exchange in this award.
Establishment of the New England Kidney Exchange Program (NEPKE):
Surgeon Frank Delmonico, Susan Saidman, Alvin E. Roth, Tayfun Sönmez, and
I launched New
England Program for Kidney Exchange (NEPKE)
in 2004. This is the first program that uses optimization-based mechanisms
to find kidney exchanges. NEPKE became the forerunner of the US National Kidney Exchange Program and dissolved itself in it in 2010.
The administrator of NEPKE, Ruthanne Hanto, currently administors the national program.
Establishment of the Alliance for Paired Kidney Donation (APKD):
Alvin E. Roth, Tayfun Sönmez, and I also helped the launching of the Alliance for Paired Kidney Donation
(APKD), founded by Dr. Michael
Rees and Jon Kopke through the funding of University of Toledo and University
of Cincinnati in Ohio. APKD is a cross-country kidney exchange registry.
Establishment of the US National Kidney Exchange Program:
The US National Kidney Exchange Program uses the similar principles with the APKD exchange system. I served on
the advisory board for the development of the program and coauthored the OPTN
policy proposal for the principles of the national kidney paired donation program. Here is the US
Congress Bill that clarified
that paired kidney donations do not violate the National Organ Transplant
Act and allowed for the establishement of the National Program. NEPKE dissolved itself in it to become de-facto national program in the United States: Ruthanne Hanto, the director of NEPKE, became the director of the UNOS National Program,
Compatible pairs in kidney exchange: A compatible patient-donor pair typically does not participate in exchange, as the donor directly donates to the patient. However, in many occasions the donor of such a pair has a more valuable blood type (such as O)
than that of the patient (such as A). Hence, if such pairs participated in exhange, they could potentially save an incompatible pair with reverse blood types (such as O patient - A donor) in addition to itself through a two-way exchange.
Beginning with our original paper, "Kidney Exchange," we pushed this idea. A recent paper of mine, joint with Tayfun Sonmez, on campatible pairs in kidney exchange is "Altruistically Unbalanced Kidney Exchange."
Non-simultaneous non-directed altruistic donor chains:
At APKD, we started to implement Never-Ending-Altruistic-Donor
an idea that we developed with Michael Rees and Jon Kopke.
Here is the
Boston Globe and CNN
news stories of the longest NEAD chain until March 2009, which has been documented
in our recent NEJM paper. Also you can watch and read
CBS evening news story featuring Matt Jones, the non-directed altruistic donor of the chain, surgeon Mike Rees,
and some of the patients and donors of the chain. Recently a 30-way non-simulatenous non-directed altrustic donor chain has been reported.
The National Kidney Registry (not to be confused with the US National Program) is currenty the leading organization that facilitates kidney exchanges and uses mostly NEAD chains.
Gains from larger exchanges:
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 APKD (
see a related news story). National program also uses 3-way exchanges.
Optimization and software: We
have also authored the optimization software used in NEPKE
and APKD. 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 in 2007. National progarm uses this algorithm.
Earlier optimization and two-way exchanges:
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, in 2005, The Johns
Hopkins University Transplant Center adopted a pairwise kidney exchange
scheme based on Edmonds'
Simultaneous non-directed altruistic donor chains:
In our QJE paper "Kidney
Exchange", we propose
the idea of a "w-chain exchange." Non-directed altruistic 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
Some other earlier notable press coverage:
NEAD-chain idea is based on the fact that chain
transplants initiated by non-directed altruistic donors need not be done simultaneously.
This idea was proposed in our AJT paper.
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.
Tim Harford published a story in the Financial
Times on 7/14/2007 about
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
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.
Adoption of Children in State-wide Adoption Network of Pennsylvania
Mustafa Akan, Onur Kesten, and Vince Slaugh of Carnegie Mellon University and I have been working with State-wide Adoption Network (SWAN) of Pennsylvania to improve recommendation systems for suggesting families for adoptive children.
Previous recommendation tools have been unsuccessful to be used by social workers distributed to different parts of the state, who are looking for best fits for the children up for adoption in the state network. They oftenby-passed
recommendations made by the tools and used their own limited network for finding families. We have made some improvements to their system that aims to attain higher usage rates by social workers.