Sensitivity of expanded-criteria donor kidneys to cold ischaemia time

The United Network for Organ Sharing (UNOS), working in conjunction with organ procurement organizations and transplant programmes, has recently defined a class of cadaver kidney grafts for special allocation procedures to enhance utilization of those organs. The criteria defining these expanded-criteria donor (ECD) kidneys are donor age > or = 60 yr or donor age between 50 and 59 yr plus two of the following characteristics: donor history of cerebrovascular accident (CVA), donor history of hypertension (htn), and elevated creatinine (>1.5) at any time during donor management. Kidney grafts from ECD donors carry an increased relative risk of non-function compared to other cadaver kidney grafts. The goal of the special allocation procedure is to reduce the time associated with placement by matching ECD grafts with patients previously designated as being willing to accept them. In assessing the potential impact of these allocation procedures, the sensitivity of ECD grafts to cold ischaemia time (CIT) became of great significance. Specifically, we questioned whether minimization of CIT might reduce the relative risk of poor graft function, justifying reduction of the geographical range of placement and thereby reducing the time the grafts would spend in-transit.

To assess this, we queried the SEOPF database for cadaveric kidney transplants between 1/1/1997 and 15/8/2002. There were 1312 transplants from ECD donors during this period and 8451 from non-ECD donors. Between these groups, there were no significant differences in recipient gender, ethnicity, peak and most recent panel reactive antibody (PRA). Recipients of ECD kidneys were significantly older: 50.9 +/- 13.0 yr vs. 44.9 +/- 13.9 (mean age +/- SD, P < 0.0001). There were statistically significant but very small differences in the degree of AB and DR mismatch between the groups.

Defining delayed graft function (DGF) as dialysis within the first week post-transplant and primary non-function (PNF) as dialysis within the first week and failure in the first year, we found an association with CIT as illustrated in Table 1. Overall, ECD kidneys had a significantly increased (P < 0.0001) incidence of PNF and DGF. Notably, PNF in ECD appeared to be uniformly distributed across CIT and while DGF was CIT-dependent, the DGF differences between ECD and non-ECD were fairly consistent across CIT.

While CIT minimization is potentially beneficial, ECD kidneys do not appear to be more sensitive to it than non-ECD kidneys.