Impact of Cold Ischemia Time in Kidney Transplants from Donation after Circulatory Death Donors

Background. Deceased-donor kidneys are exposed to ischemic events from donor instability during the process of donation after circulatory death (DCD). Clinicians may be reluctant to transplant DCD kidneys with prolonged cold ischemia time (CIT) for fear of an additional deleterious effect. Methods. We performed a retrospective cohort study examining US registry data between 1998 and 2013 of adult first-time kidney-only recipients of paired kidneys (derived from the same donor transplanted into different recipients) from DCD donors. Results. On multivariable analysis, death-censored graft survival (DCGS) was comparable between recipients of kidneys with higher CIT relative to paired donor recipients with lower CIT when the CIT difference was 1 hour or longer (adjusted hazard ratio, [aHR], 1.02; 95% confidence interval [CI], 0.88-1.17; n = 6276), 5 hours or longer (aHR, 0.98; 95% CI, 0.80-1.19; n = 3130), 10 hours or longer (aHR, 1.15; 95% CI, 0.82-1.60; n = 1124) or 15 hours (aHR, 1.15; 95% CI, 0.66-1.99; n = 498). There was a higher rate of primary non function in the long CIT groups for delta 1 hour or longer (0.89% vs 1.63%; P = 0.006), 5 hours (1.09% vs 1.67%, P = 0.13); 10 hours (0.53% vs 1.78%; P = 0.03), and 15 hours (0.40% vs 1.61%; P = 0.18), respectively. Between each of the 4 delta CIT levels of shorter and longer CIT, there was a significantly and incrementally higher rate of delayed graft function in the long CIT groups for delta 1 hour or longer (37.3% vs 41.7%; P < 0.001), 5 hours (35.9% vs 42.7%; P < 0.001), 10 hours (29.4% vs 44.2%, P < 0.001), and 15 hours (29.6% vs 46.1%, P < 0.001), respectively. Overall patient survival was comparable with delta CITs of 1 hour or longer (aHR, 0.96; 95% CI, 0.84-1.08), 5 hours (aHR, 1.01; 95% CI, 0.85-1.20), and 15 hours (aHR, 1.27; 95% CI, 0.79-2.06) but not 10 hours (aHR, 1.47; 95% CI, 1.09-1.98). Conclusions. These results suggest that in the setting of a prior ischemic donor event, prolonged CIT has limited bearing on long-term outcomes.