"MELD/PELD" – as of February 2002, all patients waiting for liver transplantation should know what these terms mean. Liver patients should also know their current MELD or PELD score (see article above).
Prior to implementation of the MELD/PELD system in February 2002, the allocation of deceased donor livers had been based on time waiting on the list. As the shortage of organs became critical, centers reacted by putting more patients on the list, even if they weren’t the sickest patients, to gain waiting time.
 | "...centers put patients on the list as soon as they could just to get waiting time because that’s how [prioritizing organ recipients] was decided," says Richard B. Freeman, Jr., M.D. of Tufts University, one of the key people in getting the MELD/PELD system implemented. As a result, waiting time directed care to people who weren’t necessarily the sickest. |
The concept behind this system is similar to the new lung allocation system (to be implemented in the Spring 2005) and the heart allocation system (revised in 1999). These systems are designed to direct organs to the sickest patients, but those who have the best chance of survival afterward. In order to create these systems, the experts at the United Network for Organ Sharing (UNOS) had to define criteria that measured these things. They needed to create an objective system that could be examined and verified.
How did they verify the system? Before they began to use the MELD/PELD system, they studied many different groups of patients to see if the score predicted risk of mortality. What they found was the system using the MELD/PELD score did consistently predict risk of mortality.
The MELD/PELD score, however, left some aspects of liver disease, such as ascites (fluid build up) and encephalopathy (mental confusions), out of the equation. Dr. Freeman commented on the problem of using these subjective measures, "It was never validated as foretelling anything for patients on the liver waiting list…[the liver transplant community] never checked to see if it was predicting anything." In developing the new system, the research team studied subjective variables and found that adding these variables to the equation did not significantly change how well the score would predict mortality risk.
"What this system allows us to do is to go back see what happens every time we change the policy," says Dr. Freeman. After implementing the system, they have been studying the initial and ongoing results for the overall population of transplant patients. The conclusion is that the system is effectively prioritizing the patients who are the sickest and establishing the criteria for patients to do well after transplant. Patients are getting transplanted at lower MELD scores over time and liver patient survival rates remain excellent, according to Dr. Freeman.
