Foundations of uncertainty in evaluation of nominal properties

Measurement uncertainty is a key component of metrology but, as it is defined, it does not apply to nominal properties. The possibility to define, evaluate, and express the uncertainty in the examination of nominal properties is then a critical prerequisite for a harmonized treatment of nominal properties in metrology. The assumption at the basis of this paper is that examination uncertainty can be understood in analogy with and as a generalization of measurement uncertainty. To this aim a foundational framework is introduced, grounded on a generic concept of evaluation uncertainty that applies equally to quantitative and non-quantitative evaluations. Based on this, a concept of examination uncertainty is presented and some examples of mathematical functions of examination uncertainty are proposed

The certification of anti-myeloperoxidase immunoglobulin G in human serum ERM® - DA476/IFCC

This report describes the production and certification of ERM-DA476/IFCC, a new serum protein reference material intended for the standardisation of measurements of anti-myeloperoxidase immunoglobulin G (anti-MPO IgG) antibodies. The material was produced according to ISO Guide 34:2009. The raw material used to prepare ERM-DA476/IFCC was a plasmapheresis material containing a high concentration of anti-MPO IgG. After a thorough commutability study lyophilised serum was selected as the format for the candidate reference material. Serum processing was performed based on the procedure used for the reference material ERM-DA470k/IFCC. The plasma was converted into serum which was then delipidated. After the addition of preservatives the processed serum was diluted with plasmapheresis solution containing albumin, prior to the transfer of 1 mL aliquots to glass vials. The serum was then lyophilised and the vials closed with rubber stoppers and screw caps under nitrogen atmosphere prior to storage at -70 °C. The between unit-homogeneity was quantified and stability during dispatch and storage were assessed in accordance with ISO Guide 35:2006. The material was characterised by an inter-laboratory comparison exercise performed by laboratories of demonstrated competence and with adherence to ISO/IEC 17025 , using a purified anti-MPO IgG preparation as calibrant. This was achieved using a value transfer protocol previously used in the characterisation of ERM-DA470k/IFCC. Technically invalid results were removed. However no other outliers were eliminated on statistical grounds only. Uncertainties of the certified values were calculated in accordance to the Guide to the Expression of Uncertainty in Measurement (GUM) and include uncertainties relating to possible lack of homogeneity, instability and characterisation. The material is intended for the calibration of methods and quality control. As any reference material, it can also be used for control charts or validation studies. The CRM is available in glass vials containing the lyophilised residue of 1 g serum. The minimum amount of reconstituted sample to be used is 10 μL. The CRM was accepted as European Reference Material (ERM®) after peer evaluation by the partners of the European Reference Materials consortium

Development of a certified reference material for anti-β2-glycoprotein I IgG - commutability studies.

Objectives: In this paper, we describe the steps followed for the development of a certified reference material for immunoglobulin G antibodies against β2-glycoprotein I (also known as apolipoprotein H). These steps include processing of the material, commutability, the impact of dilution, the appropriate reconstitution conditions, homogeneity and stability during transport and storage. Methods: We analysed 69 clinical samples from patients suffering from antiphospholipid syndrome with several commercial enzyme-linked immunosorbent assays (ELISA) purchased from in vitro diagnostic manufacturers. Results: Analysis of the results indicated that the candidate reference material can be safely freeze-dried, and that the user should carefully follow the reconstitution instructions as small changes in e.g. temperature may have unwanted effects. The statistical analysis of the commutability studies indicated that the analytical response of the reference material upon dilution is similar to that of clinical samples, and that correlation between results may differ from assay to assay. Finally yet importantly, the presented and developed candidate reference material is commutable for most assays tested, homogeneous and stable. Conclusions: Immunoglobulin G antibodies against β2-glycoprotein I are associated with a higher risk of thrombosis and pregnancy complications. Their measurement is essential for the diagnosis and monitoring of antiphospholipid syndrome. These antibodies are detected by specific immunoassays, routinely used in clinical diagnostics, but various of these methods show enormous variability, in part due to the lack of a reference material

A literature review of the predictive validity of European dental school selection methods

© 2018 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.Non peer reviewedPostprin

Сотрудничество в области производства стандартных образцов, финансируемого государством

Emteborg H. et al. Cooperation in publicly funded reference material production. Accred Qual Assur. 2018;23(6):371-377. DOI.org/10.1007/s00769-018-1349-1. Первоисточник статьи: Accred Qual Assur (2018) 23:371. https://doi.org/10.1007/s00769-018-1349-

First amyloid β1-42 certified reference material for re-calibrating commercial immunoassays

INTRODUCTION: Reference materials based on human cerebrospinal fluid were certified for the mass concentration of amyloid beta (Aβ)1-42 (Aβ42 ). They are intended to be used to calibrate diagnostic assays for Aβ42 . METHODS: The three certified reference materials (CRMs), ERM-DA480/IFCC, ERM-DA481/IFCC and ERM-DA482/IFCC, were prepared at three concentration levels and characterized using isotope dilution mass spectrometry methods. Roche, EUROIMMUN, and Fujirebio used the three CRMs to re-calibrate their immunoassays. RESULTS: The certified Aβ42 mass concentrations in ERM-DA480/IFCC, ERM-DA481/IFCC, and ERM-DA482/IFCC are 0.45, 0.72, and 1.22 μg/L, respectively, with expanded uncertainties (k = 2) of 0.07, 0.11, and 0.18 μg/L, respectively. Before re-calibration, a good correlation (Pearson's r > 0.97), yet large biases, were observed between results from different commercial assays. After re-calibration the between-assay bias was reduced to < 5%. DISCUSSION: The Aβ42 CRMs can ensure the equivalence of results between methods and across platforms for the measurement of Aβ42

A certified plasmid reference material for the standardisation of BCR-ABL1 mRNA quantification by real-time quantitative PCR

Serial quantification of BCR–ABL1 mRNA is an important therapeutic indicator in chronic myeloid leukaemia, but there is a substantial variation in results reported by diff