Background: The prognostic Kidney Donor Risk Index (KDRI)-developed and internally validated in the United States-is a widely used tool to predict transplant outcome of a deceased donor kidney. The KDRI is currently used for longevity matching between donors and recipients in the United States.
Methods: We aimed to externally validate the KDRIdonor-only and KDRIfull as proposed by Rao et al (2009). KDRIdonor-only consist of 10 donor factors, and KDRIfull with an additional 4 transplant factors. We used the Dutch Organ Transplantation Registry to include 3201 adult recipients transplanted from 2002 to 2012.
Results: The median Dutch KDRI was 1.21 and comparable with the year 2012 in the United States (median of 1.24). The calibration-slope was 0.98 and 0.96 for the KDRIfull and KDRIdonor-only, respectively, indicating that predictions of graft failure were on average similar. The discriminative ability (Harrell C) of the KDRIfull and the KDRIdonor-only at 5 years was 0.63 (95% confidence interval [CI], 0.62-0.64), and 0.62 (95% CI, 0.61-0.63), respectively. We found misspecification of 3 KDRI factors: age (P = 0.002), weight (P = 0.017), and cold ischemia time (P < 0.001). Adding the use of inotropic drugs before donation (P = 0.040) and the interaction between circulatory-death donor kidneys and prolonged cold ischemic time (>24 hours vs 12 hours; P = 0.059) could improve predictive ability.
Conclusions: The KDRI performs equal in the Dutch population. Discriminative ability of the KDRI indicates limited clinical use for adequate individualized decisions. An updated KDRI may contribute to a standardized policy meeting the growing demand of donor kidneys in the Eurotransplant region.