Factors Associated with Delayed Graft Function in a Universal Hypothermic Machine Perfusion Program: A Single-Center Retrospective Cohort Study

Background/Objectives: Hypothermic machine perfusion (HMP) has established itself as an evidence-based and effective preservation strategy to improve graft function and survival after kidney transplantation. It demonstrated a reduction in the incidence of delayed graft function (DGF) compared to static cold storage. However, the risk factors for DGF that persist when HMP is used universally are poorly defined. The aim of this study was to explore donor and recipient factors associated with DGF in a universal HMP kidney transplantation program. Methods: A single-center retrospective cohort included 134 consecutive deceased-donor kidney transplants (KTs). The primary endpoint was the incidence of DGF. Secondary endpoints included functional results, complications and survival during follow-up. Univariable and multivariable logistic regression models were performed to identify factors associated with DGF. Graft and patient survival were estimated by the Kaplan–Meier method. Graft function was assessed by serum creatinine (Cr) and estimated glomerular filtration rate (eGFR). Results: The overall incidence of DGF was 9.7% (n = 13). When stratified by donor type, the incidence of DGF was 13.3% (n = 10) for donors after brain death (DBD) and 5.1% (n = 3) for donors after circulatory death (DCD). DGF was associated with impaired graft function during follow-up, a longer in-hospital stay and a higher incidence of major complications. Donor diabetes mellitus (DM) (adjusted OR 4.09, 95% CI 1.14–14.62; p = 0.030) and lower recipient pre-KT hemoglobin (Hb) (adjusted OR 0.62 per 1 g/dL, 95% CI 0.41–0.93; p = 0.021) were associated with DGF; Firth penalized estimates were consistent, but the association with donor DM was attenuated after adjustment for donor age and CIT (OR 3.38, 95% CI 0.91–12.00). Overall graft and patient survival were 99.3% and 100%, respectively, at 12 months, and 99.3% and 96.9%, respectively, at 36 months. Conclusions: Lower recipient pre-KT Hb was consistently associated with DGF in this exploratory cohort, whereas the association with donor DM was attenuated after adjustment for donor age and CIT. Within this universal HMP program, DGF incidence did not differ significantly between DBD and DCD grafts; however, in the absence of an SCS comparator, this observation cannot be attributed to HMP. Given the limited number of events (n = 13), the lack of detailed donor DM information and the absence of PRA data, these findings are hypothesis-generating and require validation in larger prospective studies.