Current status of waitlist mortality and transplant probability for adult candidates with chronic end-stage liver disease for deceased donor liver transplantation under the Model for End-Stage Liver Disease score-based allocation policy in Japan.

Abstract

Background: In Japan's deceased-donor liver transplantation (DDLT), a new allocation policy based on the Model for End-Stage Liver Disease (MELD) score, including the exceptional MELD system (Ex-MELD), which periodically assigns additional points to the basal MELD score, was implemented in May 2019. We assessed the current state of this system for adult candidates with chronic end-stage liver disease.

Methods: Adult candidates (≥ 18 years) registered in the Japan Organ Transplant Network for DDLT as Status 2 cases (including chronic end-stage liver disease patients) between May 2019 and April 2023 were evaluated. We divided them into the MELD, Ex-MELD (major) [start 16 points, 2 points by 180 days], and Ex-MELD [hepatocellular carcinoma (HCC)] groups. Transplant probability and waitlist mortality rates were compared using competing risk analyses. The annual proportion of DDLT and the transition of median MELD at transplantation were also investigated.

Results: There were 757 candidates in MELD,126 in Ex-MELD (major), and 99 in Ex-MELD (HCC) groups. The transplant probability rates were not significantly different (3-year transplant probability rate; MELD: 24.0% vs. Ex-MELD (major): 21.0% vs. Ex-MELD (HCC): 24.1%). The rate in the Ex-MELD (major) increased dramatically as the waiting period lengthened. The waitlist mortality rates in the Ex-MELD (major) group were significantly lower (3-year waitlist mortality rate; MELD: 50.5% vs. Ex-MELD (major): 25.0% vs. Ex-MELD (HCC): 57.0%). Although the proportion of Ex-MELD (major) increased yearly in the transplanted cases, the median MELD at transplantation did not change significantly.

Conclusions: We clearly showed the current status of adult Status 2 candidates.