The MELD System for Liver Allocation

Abstract

The recent implementation of the Model for End-stage Liver Disease (MELD)/Pediatric End-stage Liver Disease (PELD) system for the allocation of cadaveric liver organs in the US represents a dramatic change in organ allocation policy. Previous allocation algorithms used a categorical stratification system, in which candidates were ranked by the length of time waiting within these strata. This resulted in the ranking of patients by time waiting on the list, not by their need for a transplant. Moreover, these previous systems had not been validated for their accuracy in predicting the severity of liver disease and did not meet the needs of the enlarging population of appropriate candidates with end-stage liver disease. The MELD was identified as a potentially more accurate measure of liver disease, and a new plan for liver allocation incorporating the MELD score and virtually eliminating waiting time was devised. Several diagnoses for which liver transplantation is indicated were identified as not being served by the MELD system, so alternative mechanisms were developed for these cases. The new allocation system went into effect on February 27, 2002. One year after implementation, there was a statistically significant increase in the number of cadaveric transplants and a slight reduction in the number of waiting list deaths compared with the previous system in the year prior to MELD.

As the system evolves and improvements are made, patients have a much more objective measure of the severity of their liver disease, which is comparable regardless of the geographic location or physician. This change to a mathematically-based system that defines the risk of death represents a change in the way patients and caregivers will think about the liver transplant list. In addition, payors now have a much more objective measure of the severity of illness and can more accurately risk-adjust their comparisons of centers and patients. The new system directs organs to sicker patients, and waiting candidates are likely to experience significant declines in their quality of life while waiting. In addition, because this new policy will result in more severely ill patients receiving transplants, the costs of care are likely to increase, although preliminary results suggest that survival rates have not changed. The change to this new, more evidence-based system is a significant paradigm shift in organ allocation policy. Patients, caregivers, and payors should also be prepared for continuous evolution of the system as more data become available.