Abstract Background Hypothermic machine perfusion (HMP) has surged in popularity to ameliorate renal IRI. Continuous-HMP (cHMP) has shown clear benefits over SCS, whereas randomised trials on short-duration end-ischemic-HMP (eiHMP) have shown no benefit. In this study, we aimed to assess the association of different HMP timings with outcome, and whether HMP modulates the negative impact of increasing cold preservation-time Methods This cohort study used UNOS data (2010–2024). Multivariable regression models, with interaction terms, were used to analyse associations, and restricted cubic spline modelling accounted non-linear relationships Results All HMP timings, versus SCS, were significantly associated with reduced DGF (cHMP:aOR = 0.484, 95%c.i. = 0.467–0.501; eiHMP:aOR = 0.459, 95%c.i. = 0.435–0.485) and shorter hospital LOS (n = 137 835). Non-linear interaction analyses revealed HMP mitigated the negative effect of additional hours of cold preservation-time compared with SCS (interaction P 0.001). cHMP showed benefit across all cold preservation-times, whereas eiHMP was beneficial only in the setting of prolonged cold preservation-time. The effect of HMP varied by donor type, with greater benefit observed in DCD grafts beyond benefits already seen in DBD grafts. Additionally, the protective effect of eiHMP appeared at shorter cold preservation-times in DCD compared with DBD grafts. HMP was also associated with significantly improved 5-year graft and patient survival. Conclusions HMP reduced the negative effects of additional hours of cold preservation-time. Therefore, the treatment effect of HMP was not fixed and increased with longer cold preservation-time. eiHMP improved outcome only at prolonged cold preservation-time. The association of HMP with improved 5-year graft survival and mortality provides real-world IDEAL stage 4 evidence.
Amarnath et al. (2026) studied this question.