title: Continuous improvement of medical test reliability using reference methods and matrix-corrected target values in proficiency testing schemes: application to glucose assay.
abstract: The reliability of biological tests is a major issue for patient care in terms of public health that involves high economic stakes. Reference methods, as well as regular external quality assessment schemes (EQAS), are needed to monitor the analytical performance of field methods. However, control material commutability is a major concern to assess method accuracy. To overcome material non-commutability, we investigated the possibility of using lyophilized serum samples together with a limited number of frozen serum samples to assign matrix-corrected target values, taking the example of glucose assays. Trueness of the current glucose assays was first measured against a primary reference method by using human frozen sera. Methods using hexokinase and glucose oxidase with spectroreflectometric detection proved very accurate, with bias ranging between -2.2% and +2.3%. Bias of methods using glucose oxidase with spectrophotometric detection was +4.5%. Matrix-related bias of the lyophilized materials was then determined and ranged from +2.5% to -14.4%. Matrix-corrected target values were assigned and used to assess trueness of 22 sub-peer groups. We demonstrated that matrix-corrected target values can be a valuable tool to assess field method accuracy in large scale surveys where commutable materials are not available in sufficient amount with acceptable costs.
authors.affiliation: Laboratoire National de Métrologie et d'Essais, Department of Biomedical and Organic Chemistry, Paris, France. Vincent.delatour@lne.fr
authors.forename: Vincent
authors.initials: V
authors.lastname: Delatour
authors.forename: Beatrice
authors.initials: B
authors.lastname: Lalere
authors.forename: Karène
authors.initials: K
authors.lastname: Saint-Albin
authors.forename: Maryline
authors.initials: M
authors.lastname: Peignaux
authors.forename: Jean-Marc
authors.initials: JM
authors.lastname: Hattchouel
authors.forename: Gilles
authors.initials: G
authors.lastname: Dumont
authors.forename: Jacques
authors.initials: J
authors.lastname: De Graeve
authors.forename: Sophie
authors.initials: S
authors.lastname: Vaslin-Reimann
authors.forename: Philippe
authors.initials: P
authors.lastname: Gillery
mesh_terms: D001774:Blood Chemical Analysis / Q000379:methods* / Q000592:standards*; D001786:Blood Glucose / Q000032:analysis*; D001800:Blood Specimen Collection; D003625:Data Collection; D005612:Freeze Drying; D008401:Gas Chromatography-Mass Spectrometry; D006801:Humans; D007753:Laboratories; D011786:Quality Control; D012015:Reference Standards; D015203:Reproducibility of Results
chemical_list: D001786:Blood Glucose