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

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.