Tsang Lau, Jawad Ahmad
Division of Liver Diseases, Mount Sinai School of Medicine, New York, USA
Abstract: The Model for End-Stage Liver Disease (MELD) score incorporates serum bilirubin, creatinine, and the international normalized ratio (INR) into a formula that provides a continuous variable that is a very accurate predictor of 90-day mortality in patients with cirrhosis. It is currently utilized in the United States to prioritize deceased donor organ allocation for patients listed for liver transplantation. The MELD score is superior to other prognostic models in patients with end-stage liver disease, such as the Child–Turcotte–Pugh score, since it uses only objective criteria, and its implementation in 2002 led to a sharp reduction in the number of people waiting for liver transplant and reduced mortality on the waiting list without affecting posttransplant survival. Although mainly adopted for use in patients waiting for liver transplant, the MELD score has also proved to be an effective predictor of outcome in other situations, such as patients with cirrhosis going for surgery and patients with fulminant hepatic failure or alcoholic hepatitis. Several variations of the original MELD score, involving the addition of serum sodium or looking at the change in MELD over time, have been examined, and these may slightly improve its accuracy. The MELD score does have limitations in situations where the INR or creatinine may be elevated due to reasons other than liver disease, and its implementation for organ allocation purposes does not take into consideration several conditions that benefit from liver transplantation. The application of the MELD score in prioritizing patients for liver transplantation has been successful, but further studies and legislation are required to ensure a fair and equitable system.
Keywords: MELD score, liver transplantation
Cirrhosis is typically a progressive condition characterized by marked fibrosis and nodule formation in the liver due to a number of causes. It is usually irreversible and led to over 30,000 deaths in the United States in 2009, making it the 12th leading cause of mortality.1 Cirrhotic patients can have well-compensated disease with little or no symptoms or present with decompensated disease, including ascites, encephalopathy, or gastrointestinal bleeding, due to portal hypertension. These latter patients are candidates for liver transplantation (LT).2
There are currently 15,000 patients awaiting LT in the United States, and only 6000–6500 transplants are performed annually; meanwhile, there is a 10% rate of death on the waiting list.3 Historically, allocation of deceased donor (DD) organs for LT was based primarily upon the amount of time a patient spent on the waiting list and subjective measures of disease severity. In 1998, the US Department of Health and Human Services issued its “Final Rule,” calling on the transplant community to establish a set of objective criteria in prioritizing patients for transplant that were most at need.4 Subsequently, the Model for End-Stage Liver Disease (MELD) was developed and adapted as a prognostic tool in advanced liver disease and is now used by UNOS to prioritize DD organ allocation for patients listed for LT.5 The validity of the MELD score has since been shown in a variety of clinical scenarios to prognosticate the outcome in patients with advanced liver disease.