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Models that Matter; Making Organ Allocation Fair

Mathematics Green Chair Colloquium

Speaker: Sommer Gentry (United States Naval Academy and Johns Hopkins University School of Medicine)

Abstract: In some areas of the U.S., the sickest liver transplant candidates have an 82% chance of dying; in others, a 14% chance of dying, because of extreme disparities in the availability of livers for transplant. Organs are shared within a hierarchy of 50 small donor service areas grouped into 11 regions, and these areas have very different ratios of eligible liver donors to liver transplant candidates. We designed novel regions for liver allocation by partitioning the set of donor service areas according to an integer program redistricting model. Our work directly addressed the paramount clinical and ethical concern about geographic equity in transplantation.  We validated our redistricted maps using the clinically detailed Liver Simulated Allocation Model that is the gold standard for testing allocation policy proposals, to compensate for the necessarily simplified and aggregated picture of liver allocation in an integer program. Trying to implement this solution led to an intense battle over the scarce livers that has had a number of twists and turns, and I will discuss a web of related studies our research group has undertaken to support the movement towards transplant equity.


Sommer Gentry is Professor of Mathematics at the United States Naval Academy, and is also on the faculty of the Johns Hopkins University School of Medicine. She is a senior investigator with the U.S. Scientific Registry for Transplant Recipients. She has a B.S. in Mathematical and Computational Science and an M.S. in Operations Research, both from Stanford University, and a Ph.D. in Electrical Engineering and Computer Science from MIT.

Professor Gentry builds operations research models to improve access to organ transplantation. She has ignited revolutionary changes in the distribution of organs for transplant, by showing that redistricting U.S. liver allocation areas would reduce geographic disparity in access to liver transplants and save hundreds of lives each year.  She also designed optimization methods to maximize the number of kidney transplants possible through kidney exchanges, and served as an advisor to the United States and Canada in their efforts to create national paired donation registries. Her work helped convince Congress to clarify the legal status of kidney paired donation in December 2007.

Her research is funded by the National Institutes of Health and her findings have been highlighted in major media outlets including Scientific American, Time Magazine, Reader’s Digest, Science, the Discovery Channel, and National Public Radio.  Gentry has also received the MAA’s Henry L. Alder award for distinguished teaching.

Wednesday, February 26 at 1:00 pm to 1:50 pm

William E. and Jean Jones Tucker Technology Center, 243

Event Type

Lectures & Presentations

Target Audience

Students, Faculty & Staff


Academic, Research, Science & Technology


Green Honors Chair Program

Mathematics, College of Science & Engineering
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