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Clin Chem. 2017 Apr;63(4):833-841. doi: 10.1373/clinchem.2016.264325. Epub 2017 Feb 10.

Multicenter Evaluation of Cystatin C Measurement after Assay Standardization.

Author information

1
Laboratoire de Biochimie, CHRU de Montpellier, PhyMedExp, University of Montpellier, INSERM U1046, CNRS UMR 9214, Montpellier cedex 5, France.
2
Laboratoire de Biologie Médicale, Centre Hospitalier d'Avignon, Avignon, France.
3
Laboratoire de Biochimie, CHRU de Montpellier, PhyMedExp, University of Montpellier, INSERM U1046, CNRS UMR 9214, Montpellier cedex 5, France; jp-cristol@chu-montpellier.fr.
4
Department of Nephrology, Dialysis and Hypertension, University of Liege, CHU Sart-Tilman, Liege, Belgium.
5
Fédération de Biochimie, Centre Hospitalier Lyon Sud, Pierre Bénite, France.
6
Laboratoire de Biochimie et Hormonologie, Hôpital tenon, APHP, Paris, France.
7
Laboratoire de Biochimie Métabolique et Cellulaire, Hôpital Bichat-Claude Bernard, APHP, Paris, France.
8
Laboratoire d'Immunochimie, Centre Hospitalier Lyon Sud, Pierre Bénite, France.
9
Department of Physical and Analytical Chemistry, Faculty of Chemistry, University of Oviedo, Oviedo, Spain.
10
Department of Clinical Chemistry, University of Liege, CHU Sart-Tilman, Liege, Belgium.
11
Laboratoire National de Métrologie et d'Essais (LNE), Paris, France.

Abstract

BACKGROUND:

Since 2010, a certified reference material ERM-DA471/IFCC has been available for cystatin C (CysC). This study aimed to assess the sources of uncertainty in results for clinical samples measured using standardized assays.

METHODS:

This evaluation was performed in 2015 and involved 7 clinical laboratories located in France and Belgium. CysC was measured in a panel of 4 serum pools using 8 automated assays and a candidate isotope dilution mass spectrometry reference measurement procedure. Sources of uncertainty (imprecision and bias) were evaluated to calculate the relative expanded combined uncertainty for each CysC assay. Uncertainty was judged against the performance specifications derived from the biological variation model.

RESULTS:

Only Siemens reagents on the Siemens systems and, to a lesser extent, DiaSys reagents on the Cobas system, provided results that met the minimum performance criterion calculated according to the intraindividual and interindividual biological variations. Although the imprecision was acceptable for almost all assays, an increase in the bias with concentration was observed for Gentian reagents, and unacceptably high biases were observed for Abbott and Roche reagents on their own systems.

CONCLUSIONS:

This comprehensive picture of the market situation since the release of ERM-DA471/IFCC shows that bias remains the major component of the combined uncertainty because of possible problems associated with the implementation of traceability. Although some manufacturers have clearly improved their calibration protocols relative to ERM-DA471, most of them failed to meet the criteria for acceptable CysC measurements.

PMID:
28188233
DOI:
10.1373/clinchem.2016.264325
[Indexed for MEDLINE]
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