Models predicting the natural history of cirrhosis and need for liver transplantation

As the gap between the demand and supply of donor organs for liver transplantation continues to increase, policy makers have grappled with alternative strategies for optimal organ allocation. An ideal allocation system should incorporate accurate measures of the severity of liver disease in order to evaluate the risk of disease progression and death. The current allocation system is based on the Child-Turcotte-Pugh (CTP) system. Although the CTP system is useful in clinical decision making as a measure of liver disease severity, it has a number of limitations in determining organ allocation priority; for example, the small number of scores available in the CTP system limits its discriminant ability. Consequently, emphasis is given to waiting time in determining priority among candidates with the same score. A new system, referred to as the Model for End-stage Liver Disease (MELD), has been developed, validated, and proposed to be used in determining organ allocation priority for liver transplantation, essentially replacing the CTP system. The model is based on three variables, including the serum concentrations of total bilirubin and creatinine and the international normalization ratio of prothrombin time. A considerable amount of data have been generated to indicate that MELD is a reliable measure of short- to medium-term mortality risk in patients with end-stage liver disease. These data demonstrate that the MELD scale is consistent with the criteria proposed by the Institute of Medicine for the disease severity index to determine organ allocation priorities.