Influence of Cold Ischemia Time in Combination with Donor Acute Kidney Injury on Kidney Transplantation Outcomes Abstract presented at the American Society of Transplant Surgeons Winter Symposium, Miami, FL, January 2015.

Background Deceased-donor kidneys are often exposed to ischemic events from donor instability, as evidenced by acute kidney injury (AKI). Clinicians may be reluctant to transplant kidneys with AKI that also have prolonged cold ischemia time (CIT) for fear of an additional deleterious effect. Study Design We evaluated national data between 1998 and 2013 of adult first-time kidney-only recipients of paired kidneys from donors with AKI (terminal serum creatinine ≥ 2 mg/dL), in which the CIT difference between recipients was ≥1, 5, 10, or 15 hours. Results On multivariate analysis of AKI kidney recipients, overall death-censored graft survival (DCGS) was comparable between recipients with higher CIT relative to paired donor recipients with lower CIT when the CIT difference was at least 1 hour (adjusted hazard ratio [aHR] 0.98, 95% CI 0.85 to 1.13, n = 4,458), 5 hours (aHR 0.97, 95% CI 0.79 to 1.18, n = 2,412), 10 hours (aHR 0.82, 95% CI 0.59 to 1.15, n = 922), or 15 hours (aHR 0.94, 95% CI 0.57 to 1.58, n = 442). Overall patient survival of the longer CIT groups was comparable or protective with delta CIT of ≥1 (aHR 0.94, 95% CI 0.83 to 1.06), 5 (aHR 0.80, 95% CI 0.68 to 0.94), 10 (aHR 0.70, 95% CI 0.53 to 0.91), and 15 (aHR 0.64, 95%CI 0.43 to 0.95) hours. Between each of the 4 delta-CIT levels of shorter and longer CIT, there were no statistically significant differences in the proportion of acute rejection at delta ≥1, 5, 10, or 15 hours. Conclusions These results suggest that in the setting of a previous ischemic donor event, prolonged CIT has limited bearing on long-term outcomes. This may be important evidence that despite the occurrence of other ischemic events, kidneys with prolonged CIT offer acceptable outcomes to recipients and are a potential source to expand the donor pool.