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Kidney Week

Abstract: PO2389

Kidney Filtration Markers: Accuracy and Reproducibility of Novel Serum Cystatin C Measurements in a Point-of-Care Rapid Test Platform

Session Information

Category: CKD (Non-Dialysis)

  • 2102 CKD (Non-Dialysis): Clinical, Outcomes, and Trials

Authors

  • Kalantar-Zadeh, Kamyar, University of California Irvine, Irvine, California, United States
  • Beshay, Manal, Intelligent Optical Systems, Inc., Torrance, California, United States
  • Rhee, Connie, University of California Irvine, Irvine, California, United States
  • Nguyen, Trong, Intelligent Optical Systems, Inc., Torrance, California, United States
  • Ortega, Maria, Intelligent Optical Systems, Inc., Torrance, California, United States
  • You, Amy Seung, University of California Irvine, Irvine, California, United States
  • Amel Peralta, Rene, University of California Irvine, Irvine, California, United States
  • Nguyen, Danh V., University of California Irvine, Irvine, California, United States
Background

Emerging data suggests cystatin C (CysC) as a more reliable kidney filtration marker than creatinine because it is unaffected by age, race, ethnicity, or body mass. In the US, the standard approach to assess blood-based CysC measurements is invasive phlebotomy followed by laborious blood specimen processing. There is a major unmet need for non-invasive point-of-care (POC) measurement of this kidney filtration marker. To fill this gap, we have recently developed and validated novel Enhanced Lateral Flow (ELF) immunoassays to measure CysC in human blood.

Methods

Validation of our ELF assays was performed in two steps. First, Pearson correlation and Bland-Altman analysis were used to assess the correlation, agreement and bias of ELF measurements to UCI Medical Center lab standard measurements from a set of 70 serum samples obtained from chronic kidney disease (CKD) patients. Then, Receiver Operating Characteristic (ROC) curve analysis was used to assess the medical diagnostic value of the ELF assay, with ELF assay measurements of 70 CKD samples and 20 healthy reference samples to determine ROC curve and Area Under Curve (AUC) of the assay.

Results

The ELF assay measurements showed high correlation to standard lab measurements, with Pearson r=0.94 (Figure A). Bland-Altman analysis showed bias of -0.5 mg/L for the ELF assay, which could be adjusted if it is consistent when we continue monitoring the assay on a broader concentration set of samples (Figure B). The ROC analysis showed excellent diagnostic value, with AUC=0.83, which shows potential for discriminating healthy and CKD subjects (Figure C and D).

Conclusion

We have demonstrated feasibility and validation of a novel POC assay to measure CysC in human blood-based samples. The ELF assay possesses acceptable POC characteristics, correlates well to standard laboratory measurements, and shows good diagnostic value. Future development could lead to a fully available POC measurement framework for CysC as a kidney function marker, and a potential paradigm shift in patient monitoring and care.

Funding

  • NIDDK Support