Long-term outcomes of hypothermic oxygenated machine perfusion in extended criteria donor liver transplantation

To the Editor, To address organ shortage, liver transplantation (LT) increasingly relies on extended criteria donation (ECD) grafts, despite their higher risk of post-transplant complications linked to ischaemia–reperfusion injury1. Given the rising proportion of ECD, traditional static cold storage (SCS) may not be sufficient. Dynamic preservation with hypothermic oxygenated machine perfusion (HOPE) has shown significant reductions in early allograft dysfunction (EAD) and liver-related and biliary complications2,3. However, most studies focus on short-term outcomes, and long-term data are lacking4. This single-centre observational study, conducted between January 2018 and November 2021, compared long-term outcomes between HOPE and SCS for patients undergoing LT from brain-dead ECD (DBD-ECD). All HOPE cases were conducted under the PERPHO study5, a prospective single-arm pilot study assessing short-term benefits in DBD-ECD LT, and implemented prospectively into routine practice with ongoing data collection after conclusion. Study design, endpoints, and statistical analyses are detailed in the Supplementary Methods. Briefly, to compare HOPE outcomes with SCS, a 1:2 nearest neighbour (calliper restriction: 0.2) propensity-matched (PSM) control group was selected among patients transplanted with DBD-ECD grafts in the same centre and period. All data were collected until 30 November 2024 to ensure maximum follow-up. The primary endpoint was death-censored graft survival, defined as the survival of the liver graft with and without considering death as a competing risk to avoid overestimating graft survival. Secondary endpoints included incidence of EAD according to the Olthoff criteria, primary graft non-function (PNF), and biliary and vascular complications.