# The Italian Score for Organ Allocation: A Ten-Year Monocentric Retrospective Analysis in Liver Transplantation for Hepatocellular Carcinoma

## TL;DR

This study evaluates how a new organ allocation system in Italy reduced the risk of patients dropping out of liver transplant waiting lists for hepatocellular carcinoma over ten years.

## Contribution

The study demonstrates that the Italian Score for Organ Allocation reduced dropout risk and improved intention-to-treat survival in hepatocellular carcinoma patients.

## Key findings

- The ISO era saw a significant decrease in dropout rates from 13.2% to 6.2% one year after listing.
- ISO was identified as a protective factor against dropout with a subhazard ratio of 0.43.
- Intention-to-treat survival improved significantly after ISO implementation despite no change in post-transplant survival.

## Abstract

Liver transplantation is the most effective treatment to improve survival in patients with hepatocellular carcinoma. However, the limited availability of donor organs makes fair and effective allocation essential. In 2016, Italy introduced the Italian Score for Organ Allocation, a system based on transplant benefit principles, to better prioritize patients at highest risk of being removed from the waiting list. This study evaluates the impact of the Italian Score for Organ Allocation over the past decade, focusing on changes in drop-out rates from the waiting list and post-transplant survival.

Background: The Italian Score for Organ Allocation (ISO), a transplant benefit oriented allocation system, was introduced in Italy in 2016. The main objective of this study is to identify risk factors for Drop-Out in hepatocellular (HCC) patients enlisted for LT before (Pre-ISO Era) and after ISO (ISO Era) introduction, while the secondary objective is to evaluate the survival results. Methods: CIFs for liver transplantation and Drop-Out were estimated and compared between eras. Factors associated with Drop-Out were identified through multivariable competing risks regression. Survival results were compared using the log-rank test. Results: Between 2011 and 2020, 410 patients with HCC were listed for LT. We observed 103 vs. 217 LT and 49 vs. 41 Drop-Outs (p < 0.001) during the Pre-ISO and ISO Era, respectively. In the multivariable analysis, ISO ([sHR] 0.43; 95%CI 0.28–0.66, p < 0.001) and Alcoholic Cirrhosis ([sHR] 0.27, 95%CI 0.11–0.70; p = 0.007) were revealed to be protective factors for Drop-Out. One year after listing, the CI for Drop-Out decreased from 13.2% to 6.2% (p = 0.02). Despite no differences observed in post-LT survival, a significant difference in the intention-to-treat survival from enlisting was found (p = 0.0019). Conclusions: Among other factors, ISO results were protective for the Drop-Out risk in HCC patients awaiting LT, with a benefit in ITT-OS survival.