Predictive Accuracy of Machine Perfusion Parameters for Kidney Allograft Outcome - A National Analysis Following the Commencement of Hypothermic Machine Preservation of Extended Criteria Donor (ECD) Kidneys in Germany

The PRE-MAP Kidney Study is a prospective, multicenter, observational clinical trial conducted across all German kidney transplant centers following the nationwide introduction of continuous hypothermic machine perfusion (HMP) for extended criteria donor (ECD) kidneys. The primary objective is to evaluate the association between machine perfusion parameters obtained during continuous HMP and post-transplant allograft function, with a specific focus on 12-month kidney function assessed by estimated glomerular filtration rate (eGFR). Secondary objectives include evaluating short- and mid-term transplant outcomes such as delayed graft function (DGF), primary non-function (PNF), biopsy-proven acute rejection, recipient and graft survival, and postoperative clinical course.

Rationale and Background Kidney transplantation is the standard therapy for end-stage renal disease. Due to donor organ scarcity, an increasing proportion of transplanted kidneys meet extended criteria (ECD), making them more susceptible to ischemia-reperfusion injury. Static cold storage (SCS), the conventional preservation method, has been shown to be associated with higher risks of impaired graft function in marginal organs. Continuous HMP has been introduced nationwide in Germany following the 2024 recommendations of the German Medical Association for ECD kidneys, allowing ex-vivo hypothermic perfusion during graft transport and offering the potential to improve organ viability. However, robust clinical data linking perfusion parameters-such as flow, pressure, resistance, temperature, and perfusion duration-to transplant outcomes in real-world practice remain limited. The PRE-MAP Kidney Study addresses this gap by prospectively collecting perfusion and clinical data under routine care conditions without altering allocation or clinical management.

Study Design The study is designed as a prospective, multicenter, non-interventional observational cohort trial. All participating German transplant centers will consecutively enroll eligible recipients of ECD kidneys preserved via continuous HMP. The study does not modify surgical retrieval techniques, organ allocation procedures, or clinical management protocols. Machine perfusion is performed exclusively within the national organ procurement framework of the Deutsche Stiftung Organtransplantation (DSO) using the CE-certified ORS LifePort Kidney Transporter.

Continuous HMP is initiated immediately after organ retrieval in donor hospitals per manufacturer guidelines. Perfusion-specific parameters-including flow, pressure, temperature, and perfusion duration-are automatically recorded throughout transport. Upon arrival at the recipient center, the graft is disconnected from the device and transplanted according to local standards. Postoperative and outpatient follow-up follow standard institutional routines without additional study-specific interventions. All patients are followed for 12 months post-transplantation.

Endpoints Primary Endpoint Kidney function at 12 months post-transplantation assessed by eGFR.