Introduction: Vascular renal resistance (VRR) and flow rate derived from hypothermic machine perfusion (HMP) appear to predict delayed graft function (DGF) and 1-year graft survival. Recently, a new prediction tool, the kidney donor risk index (KDRI), has been developed to estimate the post-transplant risk of kidney graft failure. We sought to evaluate whether VRR and flow rate improve the predictive power for graft outcomes of KDRI.

Methods: Cadaveric kidney grafts from the Scientific Registry of Transplant Recipients were retrospectively evaluated. Donor demographics were collected to determine the KDRI. Cases were divided into quartiles based on VRR and flow rate, evaluating graft survival by Kaplan-Meier plots. Subsequently, we looked at graft outcome predictive power of KDRI individually and by adding end HMP VRR and flow rate separately. Measured outcomes included graft survival at 3 years and DGF. Cox regression was used for survival analysis and ROC curves were constructed to illustrate KDRI and HMP parameters diagnostic performance.

Results: Nine thousand nine hundred thirty-two cadaveric kidney grafts were identified that received HMP and had pump parameters recorded in the database. Mean donor age at transplant was 41.8 years +/- 12.2, 69.7% of donors were Caucasian, 42% had stroke as cause of death, mean cold ischemia time was 23.6 hours. Donors whose grafts had higher VRR and lower flow rate were more commonly hypertensive, diabetic, had a smaller BMI and longer cold ischemia time. There were 610 grafts failure per 1000-patient months and 22.4% cases of DGF; both, graft failure and DGF, were more common in grafts with higher VRR (p<0.01) but were not significantly impacted by flow rate (p= 0.29). The ROC curve for KDRI alone had an AUC of 0.65 in predicting DGF and 0.64 in predicting 3-year graft survival. Neither VRR nor flow rate significantly change KDRI predictive power for graft outcomes.

Conclusion: KDRI predictive power is not improved by utilizing HMP renal resistance and/or flow rate suggesting that over reliance on pump parameters when making allocation decisions may result in unnecessary discard of viable donor kidneys.

« Back to 2013 American Transplant Congress