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Abstract: TH-PO732

Performance of a Novel Race-Independent GFR Estimating Equation in Kidney Transplant Recipients Based on NMR-Measured Metabolites

Session Information

Category: Diversity and Equity in Kidney Health

  • 800 Diversity and Equity in Kidney Health


  • Meeusen, Jeff W., Mayo Clinic Department of Laboratory Medicine and Pathology, Rochester, Minnesota, United States
  • Dasari, Surendra, Mayo Clinic Department of Laboratory Medicine and Pathology, Rochester, Minnesota, United States
  • Lieske, John C., Mayo Clinic Department of Laboratory Medicine and Pathology, Rochester, Minnesota, United States
  • Grassi, Marcello, numares AG, Regensburg, Germany
  • Stämmler, Frank, numares AG, Regensburg, Germany
  • Schiffer, Eric, numares AG, Regensburg, Germany

Close monitoring of GFR is essential for the management of patient's post kidney transplantation. The gold-standard tracer determined measured GFR (mGFR) is not readily accessible in most centers. Furthermore, the performance of new estimated GFR (eGFR) equations based upon creatinine and cystatin C have not been validated in kidney transplant patients. We have recently developed a novel eGFR equation that uses creatinine, cystatin C, myoinositol and valine.


Here we evaluate this new equation (eGFRNMR) along with the 2021 CKD EPI equations using creatinine alone (eGFRcr), and in combination with cystatin C (eGFRcr-cys) in a cohort of kidney transplant patients with protocol iothalamate renal clearance mGFR (n=220).


Compared to mGFR, there was no significant bias for eGFRcr or eGFRNMR, while eGFRcr-cys underestimated mGFR. P30 values were similar for all eGFR, while P15 was higher for eGFRNMR compared to eGFRcr. (Table 1) Agreement with mGFR CKD stages of <15, 30, 45, 60 and 90 mL/min/1.73m2 was identical for eGFRcr and eGFRcr-cys while eGFRNMR was significantly higher. eGFRcr concordantly classified 86% of patients below and 78% above 60mL/min/1.73m2. Applying the eGFRcr-cys method would reclassify 8.2% of patients as <60mL/min/1.73m2 and incorrectly reclassify 5.1% as >60 mL/min/1.73m2 for a net reclassification improvement (NRI) of 3.1%. The eGFRNMR method correctly reclassified 3.3% lower and 4.1% higher for a net NRI of 7.1% (Table 1).


The 2021 CKD-EPI eGFRcr and eGFRcr-cys have similar bias, P15, and agreement while eGFRNMR more closely matched mGFR among kidney transplant recipients.

Table 1
Median Difference;
mL/min/1.73m2 (95CI)
(-1.67 to 1.36)
(-4.83 to -2.51)
(-1.30 to 1.68)
P15; % (95CI)57.3
(50.7 to 63.8)
(54.5 to 67.4)
(61.1 to 73.5)
P30; % (95CI)85.0
(80.3 to 89.7)
(86.0 to 94.0)
(87.1 to 94.7)
Agreement; %(95CI)61.8
(55.4 to 68.2)
(55.4 to 68.2)
(60.1 to 72.6)
Net Reclassification
Improvement; % (95CI)
(0.8 to 5.4)
(3.9 to 10.8)

*p-values compared to eGFRcr