International Multicenter Prospective, Non-competitive, Observational Study to Validate and Optimize Prediction Models of 90-day and 1-year Allograft Failure After Liver Transplantation

Background. During the last decade, the expansion of the donor pool by using extended criteria donors (ECD) grafts and those after cardiac death (DCD) have redrawn the attention around allograft failure (AF) due to ischemia-reperfusion injury after liver transplantation. The prompt diagnosis of AF is of paramount importance to define the indication for early re-transplantation. Moreover, the grafts from ECD and DCD not only may develop AF during the initial 90 days (early allograft failure, EAF) but also a slow-evolving type of failure, which presents up until 365 days.

The evaluation times and the modalities to promptly identify AF are still the object of research. At the same time, no consensus exists on the most accurate predictors of AF and on the possible mitigation strategies. In addition, ECD and DCD grafts are burdened by a higher incidence of ischemic cholangiopathy, that typically develops after 6 to 12 months, which is also a cause of AF and need for retransplant.

Two scores, one developed in the United States at University of California Los Angeles (L-GrAFT) and one in Italy on a multicentric basis (EASE), allow the prediction of EAF with excellent C-statistics. Both were validated on multicentric external populations. L-GrAFT and EASE scores are calculated at day 10 after LT; a modification of the L-GrAFT score at day 7 has been developed and validated. Both scores are also proposed for quantifying the degree of graft recovery in translational studies. However, the prognostic role of pre-transplant histopathology of the graft as well as the detailed characterization of the dynamics that make retransplant sustainable or contraindicated and the possibilities to intervene to mitigate the graft-related risk remain unmet needs. Finally, the differences among phenotypic patterns of various transplant types (DBD, deceased donor grafts after cardiac death [DCD] and living donor grafts [LD]) have not been investigated, nor a large prospective study has been undertaken.

Rationale. Timely prediction of AF is pivotal to identify patients potentially benefiting from a rescue retransplant before severe complications develop. When massive cytolysis and clear signs of liver failure occur within the first 2-4 days after LT, the indication for a retransplant is clear, independently from the evidence of hepatic vessels thrombosis. Nevertheless, past 5 to 10 days after transplant, the decision whether or not to retransplant is often challenging. AF results from a complex interplay between donor, procurement-related, and recipient perioperative factors. All of them contribute to determine the severity and the capability to recover from the ischemia-reperfusion injury. However, several conditions and/or postoperative events may precipitate such capability (e.g., pre-operative cardiac ischemic damage, frailty-sarcopenia, graft rejection, drug toxicity, kidney failure, or severe infections or sepsis). Only a part of these factors have been studied. Additionally, although L-GrAFT and EASE scores can predict AF after 7 to 10 days, the trajectories of the graft towards recovery, successful or unsuccessful retransplantation and death without retransplant, have not been fully characterized yet. Despite the excellent accuracy and the efficacious discrimination ability, the existing studies have not elucidated the individual role of these events, nor competitive models have been developed in the perspective of retransplantation. Notably, literature is exclusively based on retrospective studies. Almost all these studies span an extended period of time, are often monocentric, do not consider the center volume effect, and are not balanced in the number of recruited patients in each center. Finally, only a small number of DCD grafts and ECD grafts managed by perfusion machines have been included in previous studies.

Study objectives: