May 30, 2001 (Atlanta) -- If you are one of the nearly 18,000 Americans waiting for a liver transplant, you already know one hard, cold fact: there aren't enough livers to go around. Last year only 5,000 patients got liver transplants, so your life depends on getting to the top of the list.
Now the rules may be changing.
The lists that determine who gets donated organs is kept by a fiercely independent nonprofit organization called the United Network for Organ Sharing or UNOS. Since the 1950s, UNOS has used the same basic system for getting livers to patients who need them most: the Child-Turcotte-Pugh (CTP) scoring system. Now it looks like they are getting ready for something new.
It's called the Model for End Stage Liver Disease or MELD. The old CTP system depended on a doctor's opinion of how bad some of a patient's symptoms had become. The MELD system doesn't ask anybody's opinion -- it is based on laboratory tests and a patient's precise diagnosis. Most studies -- but not all of them -- show that MELD works at least as well as the old system in predicting which waiting-list patients will die if they don't get the next available liver.
"Because the MELD system is felt to do a better job of stratifying patients, it gives them some assurance that if they are sick and need a new liver they are more likely to be placed at the top of the list," C. Wright Pinson, MD, MBA, tells WebMD. "The MELD system seems to do a better job of identifying the patient who is at highest risk of early death. It gives patients a better chance of appearing at the top of the list when they need to."
"We wanted a way of allocating organs to patients with roughly equal severity of illness and likelihood of transplant success," says Todd K. Howard, MD, chair of the UNOS liver allocation committee. "MELD is the first step in predicting who is the sickest patient."
Pinson, chief of liver transplantation and chief of staff at Vanderbilt University Hospital in Nashville, recently co-chaired a lively roundtable debate on the proposed new MELD standard here at the Digestive Disease Week conference.
During the conference, a group of researchers from Saint Louis University presented a study suggesting that the MELD system fails to appreciate the severity of illness in patients with several life-threatening conditions due to acute liver disease.
"Patients who are [in this category] require continuous intensive care and are at high risk of acquiring hospital infections that would disqualify them from getting a transplant," said Alex S. Befeler, MD, a liver expert at Saint Louis University, during the heated debate set off by this presentation.
Calming the waters was the elder statesman of liver allocation, Jeremiah G. Turcotte, MD. Turcotte helped develop the CTP system that bears his name. He is the newly elected president of UNOS and is emeritus professor at the University of Michigan.
"There will never be a perfect scoring system -- any system will need periodic reassessment and refinement," Turcotte says. "MELD is very promising, and its validation is an essential step. As physicians and investigators, most of us are disposed to analyze statistical tools based on scientific methods. But organ allocation is a public-policy effort. Liver-disease-severity scoring is a moving target: the waiting list is growing, the average severity of illness among patients on the list is increasing, and indications for transplant are expanding. The discrepancy between organs available and people on the waiting list is dramatic."
Whether MELD can help resolve these growing problems remains to be seen. Pinson says that UNOS now is testing the MELD system against the extensive patient histories in its database. If this study shows that MELD works at least as well as CTP, there likely will be changes in the rules of the waiting game.