Background: Machine perfusion in liver transplantation has allowed utilization of higher risk donors (older age, higher macrosteatosis, or donation after circulatory death) with improvement in outcomes compared to static cold storage. Clinical outcomes between the most common machine perfusion modalities (hypothermic and normothermic) have not been reported. Study Design: Adult deceased donor liver transplant recipients who received an allograft reported as machine perfused by the organ procurement organization were identified using 2016-2024 Organ Procurement and Transplantation Network data in the United States. Machine perfusion was categorized as hypothermic (n=235) or normothermic (n=3,897). Risks of all-cause and death-censored graft loss were quantified using propensity-weighted Cox proportional hazard models by machine perfusion modality. Results: Machine perfusion of transplanted livers increased 11-fold and 25-fold for hypothermic (2019: n=9; 2024: n=109) and normothermic (2019: n=84; 2024: n=2,167) perfusion. One-year adjusted risks of all-cause (aHR:1.00,95%CI: 0.59-1.69, p=0.99) and death-censored (aHR:1.00,95%CI: 0.43-2.35, p=1.0) graft loss were similar between the two machine perfusion types. Additionally, the cumulative incidences of primary non-function and hepatic artery thrombosis were similar among liver transplant recipients between hypothermic and normothermic machine perfusion. Conclusions: This report is the first direct comparison of outcomes among liver transplant recipients by machine perfusion modality. It demonstrates increased use of machine perfusion, and these preliminary findings suggest equivalent outcomes among liver transplant recipients with hypothermic and normothermic machine perfusion on a national level, though further study is needed.
Haugen et al. (Mon,) studied this question.