Factors associated with waiting time on the liver transplant list: an analysis of the United Network for Organ Sharing (UNOS) database

BACKGROUND: Liver transplantation (LT) is an important treatment for acute liver failure and end-stage liver disease. In 2002, the model for end-stage liver disease (MELD) score was incorporated to prioritize patients awaiting LT. Although there is data on how the MELD score affects waiting times, there is a paucity of literature regarding other components. We aimed to evaluate the factors affecting LT waiting times in the United States. METHODS: Using the United Network for Organ Sharing (UNOS) database, patients aged 12-75 years listed for LT over the years 2002-2015 were included. Variables tested in the model included patient characteristics, pertinent laboratory values, ABO blood type, region of listing, primary payer, ethnicity, and listing for simultaneous transplantation. RESULTS: A total of 75,771 patients were included in the final analysis. The components of the MELD score were associated with shorter waiting times. Other factors associated with shorter waiting times were the need of mechanical ventilation and region 3 of transplantation. ABO blood type, primary payer, and placement of a transjugular intrahepatic porto-systemic shunt also influenced time on the LT waiting list. CONCLUSIONS: MELD score is utilized in the prioritization of liver allocation, and was expected to predict waiting-list time. Mechanical ventilation and other markers of disease severity are associated with higher MELD scores and thus shorter waiting times. Further research is needed to address reasons for the variation in waiting times between regions and payment systems in an attempt to decrease time to LT, standardize the listing process, and improve patient outcomes.