Application of a continuous disease severity score to the OPTN liver waiting list

In a move to establish measurable, objective criteria for cadaveric liver allocation, the United Network for Organ Sharing OPTN will implement the Model for End Stage Liver Disease (MELD) system in early 2002 as a replacement for the current Child-Turcotte-Pugh (CTP)-based Status 2A, 2B, and 3 categories for patients waiting for a cadaver donor liver transplant. The MELD is a continuous mortality risk score based on serum creatinine, bilirubin, and INR. Although originally developed in patients undergoing the transjugular intrahepatic portosystemic shunt (TIPS) procedure, analysis of OPTN data shows that the components of MELD (in particular, bilirubin) have a very strong correlation with mortality in liver transplant candidates. Univariate analyses showed that pretransplant mortality significantly increased when the MELD score was > 1.8. In the study cohort, 25% of the patients had a MELD score > 1.8. Multivariate analysis showed that the MELD score was an independent predictor of mortality, with a 2-unit increase multiplying the risk of mortality by a factor of 5.6. The MELD and CTP scores were correlated, but MELD scores varied widely for any given CTP score, indicating that some patients could be disadvantaged with the status-based system. The MELD score was validated in an independent dataset; concordance with 3-month mortality was 0.88. We conclude that the MELD score is a good indicator of disease severity and that implementation of this system should direct more livers to those patients in greatest need of transplantation.