Can the outcome of older donor kidneys in transplantation be predicted? An analysis of existing scoring systems

The use of older cadaveric donors in kidney transplantation is increasing. The transplant outcome of the single older kidney is generally inferior prompting some to recommend dual kidney transplantation. The ability to predict the outcome of the solitary marginal kidney becomes clinically important. Such insight might allow for better allocation strategies that would minimize poorer outcomes while permitting optimal rationalization of this scarce resource. A retrospective, single center review of 79 single kidney transplants from 50 donors aged ≥55 yr was performed. We tested the validity of published scoring strategies to predict subsequent recipient kidney function. Receiver operating characteristic curve analysis was used to quantify the donor strategies separating good and poor outcomes based upon recipient creatinine clearance (CrCl) < 30 mL/min. Two pre-transplant donor assessment strategies, Nyberg score and donor CrCl (dCrCl) were found to predict subsequent kidney function in recipients. When Nyberg variables (cold ischemia time, donor diabetes and hypertension status, incremental donor age > 55 yr and cause of death in conjunction with the dCrCl were considered, they were no better than dCrCl alone. Although dCrCl had a reasonable negative predictive ability, the positive predictive value was < 50%. Our analysis suggests that a dCrCl of ≥70 mL/min is a better discriminator of subsequent kidney function outcomes than a dCrCl of 90 mL/min as recommended by the Dual Transplant Registry.