Patients secure a spot on the liver transplant list by MELD (Model for End-Stage Liver Disease) score, a snapshot of health that generally ranges from 6 to 40, with 40 indicating the direst cases. Median MELD score at transplant is a proxy for wait time because patients land on the list long before they reach a score of 40. (Hawaii and Alaska are omitted.) Image: Maps by Scientific American; Source: Corey Wickliffe
If you need a liver and live in Boston, your chance of getting one in time is about 53 percent. Drive a couple of hours southwest to Connecticut, and your chances jump to 85 percent.
The difference is encapsulated in the national organ transplant map, which divides the U.S. into self-contained districts of organ allocation. Among other factors, areas with lots of highways—and the accompanying traffic fatalities that make healthy organs available for transplant—will generally have a shorter wait time.
With optimization techniques used to draw political districts, a group of researchers from the Johns Hopkins University School of Medicine has found a potential path to help correct the liver imbalance. The researchers have proposed a redrawn map that levels the odds of receiving a liver throughout the country. A similar approach could possibly help curb inequities for other organs as well.
“By using an optimized map, we would be able to cut geographic disparities in liver allocation in half,” says study author Dorry Segev, a transplant surgeon at Johns Hopkins. In the name of fairness, some areas' chances would improve, whereas others would fall: a 79 percent chance of receiving a liver before a patient dies in Miami would drop to a 72 percent chance under the new proposal, but in New York City a 56 percent chance would improve to 68 percent. (A host of factors, including a region's organ donation rates, help to shape the odds.)
The current donation system, run by the United Network for Organ Sharing (UNOS), offers some recourse to patients in areas with long wait times. Someone in New York City, for instance, can put her name on multiple waiting lists and, if she is healthy enough to travel, can hop on a plane if and when an organ becomes available in Tennessee. Unfortunately, the cost and complexity of long-distance travel, compounded by the logistical obstacles of working with multiple transplant teams, ensure that only 4.4 percent of the almost 16,000 people on the liver transplant list do so.
UNOS says that it is exploring how it could employ Segev's methods, if not his particular map, to tweak its system in the future and better allocate livers throughout the country. The Johns Hopkins team hopes that the liver map will inspire a new distribution system for other vital organs as well. That could truly be some lifesaving technology.
This article was originally published with the title The Liver Transplant Divide.