Liver transplant allocation policies and outcomes in United States: A comprehensive review

Abstract

Liver transplant allocation policies in the United States has evolved over 3 decades. The donor liver organs are matched, allocated and procured by the Organ Procurement and Transplantation Network which is administered by the United Network of Organ Sharing (UNOS), a not-for-profit organization governed by the United States human health services. We reviewed the evolution of liver transplant allocation policies. Prior to 2002, UNOS used Child-Turcotte-Pugh score to list and stratify patients for liver transplantation (LT). After 2002, UNOS changed its allocation policy based on model for end-stage liver disease (MELD) score. The serum sodium is the independent indicator of mortality risk in patients with chronic liver disease. The priority assignment of MELD-sodium score resulted in LT and prevented mortality on waitlist. MELD-Sodium score was implemented for liver allocation policy in 2016. Prior to the current and most recent policy, livers from adult donors were matched first to the status 1A/1B patients located within the boundaries of the UNOS regions and donor-service areas (DSA). We reviewed the disadvantages of the DSA-based allocation policies and the advantages of the newest acuity circle allocation model. We then reviewed the standard and non-standard indications for MELD exceptions and the decision-making process of the National Review Liver Review Board. Finally, we reviewed the liver transplant waitlist, donation and survival outcomes in the United States.

Early Impact of MMaT-3 Policy on Liver Transplant Waitlist Outcomes for Hepatocellular Carcinoma

“…In February 4, 2020, the new AC model was reinstated by UNOS for liver distribution. 20 That means MMaT-3 was calculated on DSA-level characteristics during the pre-AC period of MMaT policy and distance-level characteristics during the AC period of MMaT policy. Therefore, categorizing patients as low, medium, and high MELD based on UNOS regions subjects HCC recipients in both the MMaT analysis and AC subanalysis to misclassification of exposure and significant type II error.…”

Abdominal Organ Transplantation: Noteworthy Literature in 2022

“…Latt and colleagues provided a good overview of the evolution of LT allocation policies. 77 Before 2002, UNOS used the Child-Turcotte-Pugh score to list and stratify patients for LT. After 2002, UNOS changed its allocation policy based on MELD score. Serum sodium (Na), an independent indicator of mortality risk in patients with chronic liver disease, was added to the MELD calculation in 2016.…”

The Evolution of the MELD Score and Its Implications in Liver Transplant Allocation: A Beginner's Guide for Trainees

“…The inclusion of serum creatinine into the score imprecisely reflects true renal function. 9 , 10 Individuals with lower muscle mass (ie, sarcopenia) may have lower serum creatinine levels inaccurately reflecting their true renal function. 11 Similarly, women have less muscle mass compared with male counterparts and, therefore, have reduced creatinine levels disadvantaging their MELD-Na score prioritization on the waitlist.…”