Assessing the efficacy of hypothermic oxygenated and non-oxygenated machine perfusion in kidney transplantation: a systematic review and network meta-analysis

Background: This systematic review and Bayesian network meta-analysis aimed to evaluate and compare the relative efficacy of hypothermic oxygenated machine perfusion (HOPE) and hypothermic machine perfusion (HMP) for kidney preservation in terms of delayed graft function (DGF), acute rejection, and primary non-function (PNF). Methods: The review adhered strictly to the PRISMA 2020, AMSTAR and TITAN guidelines and was registered on PROSPERO. PubMed, Embase, and the Cochrane Central Register of Controlled Trials were comprehensively searched up to February 2025. Randomized controlled trials (RCTs) and quasi-RCTs comparing HOPE, HMP, and static cold storage (SCS) for human donor kidneys were included. Two reviewers independently screened and extracted data, assessed bias using RoB 2, and graded the certainty of evidence with the GRADE approach. Data synthesis involved Bayesian network meta-analysis using R (gemtc package). Results: A total of 18 RCTs involving 3505 patients were analyzed. Compared to SCS, HOPE (RR = 0.67; 95% CI: 0.45–1.00; moderate-certainty) and HMP (RR = 0.65; 95% CI: 0.56–0.76; high-certainty) significantly reduced DGF. However, the network estimate for HOPE vs HMP showed no significant differences for DGF (RR = 1.00; 95% CI: 0.69–1.50; low-certainty) or for acute rejection (RR = 0.84; 95% CI: 0.50–1.40; low-certainty). Both HOPE and HMP were comparably effective in reducing PNF relative to SCS. Conclusions: Based on high-certainty evidence, HMP continues to represent the standard of care for reducing DGF in kidney preservation. However, limited and imprecise head-to-head evidence shows no clear advantage of HOPE over HMP in reducing DGF or acute rejection. Further robust, multicenter RCTs are warranted to clarify these preliminary findings.