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World J Methodol. Jan 20, 2022; 12(1): 32-42
Published online Jan 20, 2022. doi: 10.5662/wjm.v12.i1.32
Liver transplant allocation policies and outcomes in United States: A comprehensive review
Nyan L Latt, Mumtaz Niazi, Nikolaos T Pyrsopoulos
Nyan L Latt, Mumtaz Niazi, Nikolaos T Pyrsopoulos, Division of Gastroenterology and Hepatology, Department of Medicine, Rutgers-New Jersey Medical School, Newark, NJ 07101-1709, United States
Author contributions: Latt NL and Niazi M researched, planned, outlined and wrote the entire manuscript; Pyrsopoulos NT advised the outline, reviewed and edited the manuscript.
Conflict-of-interest statement: Dr. Pyrsopoulos reports grants from MALLINCKRODT, grants from VALEANT, grants from GILEAD, grants and other from BAYER, grants from BEIGENE, grants from GENFIT, grants from PROMETHEUS, grants from GRIFOLS, grants from INTERCEPT, grants from ZYDUS, grants and other from EISAI, other from ROCHE, grants from ABBVIE, grants from NOVARTIS, outside the submitted work.
Open-Access: This article is an open-access article that was selected by an in-house editor and fully peer-reviewed by external reviewers. It is distributed in accordance with the Creative Commons Attribution NonCommercial (CC BY-NC 4.0) license, which permits others to distribute, remix, adapt, build upon this work non-commercially, and license their derivative works on different terms, provided the original work is properly cited and the use is non-commercial. See:
Corresponding author: Nikolaos T Pyrsopoulos, MD, PhD, Professor, Division of Gastroenterology and Hepatology, Department of Medicine, Rutgers-New Jersey Medical School, 185 S. Orange Avenue MSB H Rm–536, Newark, NJ 07101-1709, United States.
Received: February 24, 2021
Peer-review started: February 24, 2021
First decision: May 6, 2021
Revised: June 21, 2021
Accepted: November 12, 2021
Article in press: November 12, 2021
Published online: January 20, 2022

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.

Keywords: Liver transplant, Allocation, Distribution, Waiting list, Policies, Acuity circles, Transplant exceptions, National Review Liver Review Board

Core Tip: The liver transplant donor allocation and distribution polices have evolved over three decades. The liver donor distribution policy has recently changed from donor-service area-based policy to the acuity circle model. The new policy is believed to work more efficiently and equitably for waitlist candidates across the United States.