Donor Warm Ischemia Time Modifies Susceptibility to Cold Ischemia in Donation After Circulatory Death Kidney Allografts Under Hypothermic Machine Perfusion.

BACKGROUND

Donation after circulatory death (DCD) kidneys are exposed to donor warm ischemia time (dWIT) in addition to cold ischemia. Although porcine studies suggest synergy between these insults, evidence in clinical transplantation is limited.

METHODS

Adult DCD kidney-only transplants performed using hypothermic machine perfusion (n = 28 698) in the United Network for Organ Sharing database (January 1, 2015, to December 31, 2023) were included. We performed 1:1:1 propensity score matching across 3 cold ischemia time (CIT) categories (short, <18 h; intermediate, 18-23 h; and long, ≥24 h) on the Kidney Donor Profile Index and estimated posttransplant survival. The incidence of delayed graft function and 5-y graft survival was evaluated in the matched cohort (6885 per group) and subgroups of dWIT (≤30, 31-45, and ≥46 min).

RESULTS

CIT categories stratified 5-y graft survival: 76.1% in short CIT, 73.9% in intermediate CIT, and 72.1% in long CIT. Compared with short CIT group, recipients in the long CIT (≥24 h) group had higher hazards of graft loss across dWIT subgroups (for dWIT ≤30 min: hazard ratio [HR], 1.11 [95% confidence interval (CI), 1.01-1.22]; for dWIT 31-45 min: HR, 1.31 [95% CI, 1.10-1.56]; and for dWIT ≥46 min: HR, 1.56 [95% CI, 1.25-1.93]). A similar interaction was observed for delayed graft function incidence.

CONCLUSIONS

Prolonged dWIT increases DCD kidney susceptibility to CIT, and DCD kidneys with dWIT ≥46 min resulted in detrimental graft survival when CIT exceeds ≥24 h. For DCD kidney transplantation using hypothermic machine perfusion, CIT should be minimized in kidneys with prolonged dWIT.