Irregular analytical errors in diagnostic testing – a novel concept

AbstractBackground:In laboratory medicine, routine periodic analyses for internal and external quality control measurements interpreted by statistical methods are mandatory for batch clearance. Data analysis of these process-oriented measurements allows for insight into random analytical variation and systematic calibration bias over time. However, in such a setting, any individual sample is not under individual quality control. The quality control measurements act only at the batch level. Quantitative or qualitative data derived for many effects and interferences associated with anindividualdiagnostic sample can compromise any analyte. It is obvious that a process for a quality-control-sample-based approach of quality assurance is not sensitive to such errors.Content:To address the potential causes and nature of such analytical interference in individual samples more systematically, we suggest the introduction of a new term called theirregular(individual)analytical error. Practically, this term can be applied in any analytical assay that is traceable to a reference measurement system. For an individual sample an irregular analytical error is defined as an inaccuracy (which is the deviation from a reference measurement procedure result) of a test result that is so high it cannot be explained by measurement uncertainty of the utilized routine assay operating within the accepted limitations of the associated process quality control measurements.Summary:The deviation can be defined as the linear combination of the process measurement uncertainty and the method bias for the reference measurement system. Such errors should be coinedirregular analytical errorsof the individual sample. The measurement result is compromised either by an irregular effect associated with the individual composition (matrix) of the sample or an individual single sample associated processing error in the analytical process.Outlook:Currently, the availability of reference measurement procedures is still highly limited, but LC-isotope-dilution mass spectrometry methods are increasingly used for pre-market validation of routine diagnostic assays (these tests also involve substantial sets of clinical validation samples). Based on this definition/terminology, we list recognized causes of irregular analytical error as arisk catalogfor clinical chemistry in this article. These issues include reproducible individual analytical errors (e.g. caused by anti-reagent antibodies) and non-reproducible, sporadic errors (e.g. errors due to incorrect pipetting volume due to air bubbles in a sample), which can both lead to inaccurate results and risks for patients.

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The IFCC Reference Measurement System for HbA1c: A 6-Year Progress Report

Clinical Chemistry ◽

10.1373/clinchem.2007.097402 ◽

2008 ◽

Vol 54 (2) ◽

pp. 240-248 ◽

Cited By ~ 127

Author(s):

Cas Weykamp ◽

W Garry John ◽

Andrea Mosca ◽

Tadao Hoshino ◽

Randie Little ◽

...

Keyword(s):

Measurement System ◽

Clinical Chemistry ◽

Essential Elements ◽

Systematic Change ◽

Data Sets ◽

Reference Measurement ◽

Assigned Value ◽

The Mean ◽

The Stability ◽

Reference Measurement System

Abstract Background: The IFCC Reference Measurement System for hemoglobin (Hb)A1c (IFCC-RM) has been developed within the framework of metrologic traceability and is embedded in a network of 14 reference laboratories. This paper describes the outcome of 12 intercomparison studies (periodic evaluations to control essential elements of the IFCC-RM). Methods: Each study included: unknown samples (to test individual network laboratories); known samples (controls); recently manufactured calibrators (to check calculated assigned value); stored calibrators (to test stability) and a calibration-set (to calibrate the IFCC-RM). The unknown samples are measured by use of the IFCC-RM and the designated comparison methods [DCMs; the National Glycohemoglobin Standardization Program (NGSP) in the US, Japanese Diabetes Society/Japanese Society for Clinical Chemistry (JDS/JSCC) in Japan, and Mono-S in Sweden] are used to investigate the stability of the Master Equation (ME), the relationship between IFCC-RM and DCMs. Results: A total of 105 IFCC-RM data sets were evaluated: 95 were approved, 5 were not, and for 5 no data were submitted. Trend analysis of the MEs, expressed as change in percentage HbA1c per year, revealed 0.000% (NGSP, not significant), −0.030%, (JDS/JSCC; significant) and −0.016% (Mono-S; not significant). Evaluation of long-term performance revealed no systematic change over time; 2 laboratories showed significant bias, 1 poor reproducibility. The mean HbA1c determined by laboratories performing mass spectrometry (MS) was the same as the mean determined by laboratories using capillary electrophoresis (CE), but the reproducibility at laboratories using CE was better. One batch of new calibrators was not approved. All stored calibrators were stable. Conclusion: A sound reference system is in place to ensure continuity and stability of the analytical anchor for HbA1c.

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Towards an SI-Traceable Reference Measurement System for Seven Serum Apolipoproteins Using Bottom-Up Quantitative Proteomics: Conceptual Approach Enabled by Cross-Disciplinary/Cross-Sector Collaboration

Clinical Chemistry ◽

10.1093/clinchem/hvaa239 ◽

2020 ◽

Author(s):

Christa M Cobbaert ◽

Harald Althaus ◽

Ilijana Begcevic Brkovic ◽

Uta Ceglarek ◽

Stefan Coassin ◽

...

Keyword(s):

Mass Spectrometry ◽

Cardiovascular Disease ◽

Measurement System ◽

Protein Quantification ◽

Test Results ◽

Conceptual Approach ◽

Reference Measurement ◽

Lipid Panel ◽

Mass Spectrometry Technology ◽

Reference Measurement System

Abstract Current dyslipidemia management in patients with atherosclerotic cardiovascular disease (ASCVD) is based on traditional serum lipids. Yet, there is some indication from basic research that serum apolipoproteins A-I, (a), B, C-I, C-II, C-III, and E may give better pathophysiological insight into the root causes of dyslipidemia. To facilitate the future adoption of clinical serum apolipoprotein (apo) profiling for precision medicine, strategies for accurate testing should be developed in advance. Recent discoveries in basic science and translational medicine set the stage for the IFCC Working Group on Apolipoproteins by Mass Spectrometry. Main drivers were the convergence of unmet clinical needs in cardiovascular disease (CVD) patients with enabling technology and metrology. First, the residual cardiovascular risk after accounting for established risk factors demonstrates that the current lipid panel is too limited to capture the full complexity of lipid metabolism in patients. Second, there is a need for accurate test results in highly polymorphic and atherogenic apolipoproteins such as apo(a). Third, sufficient robustness of mass spectrometry technology allows reproducible protein quantification at the molecular level. Fourth, several calibration hierarchies in the revised ISO 17511:2020 guideline facilitate metrological traceability of test results, the highest achievable standard being traceability to SI. This article outlines the conceptual approach aimed at achieving a novel, multiplexed Reference Measurement System (RMS) for seven apolipoproteins based on isotope dilution mass spectrometry and peptide-based calibration. This RMS should enable standardization of existing and emerging apolipoprotein assays to SI, within allowable limits of measurement uncertainty, through a sustainable network of Reference Laboratories.

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A New Flatness Reference Measurement System Based on Deflectometry and Difference Deflectometry

Fringe 2009 ◽

10.1007/978-3-642-03051-2_52 ◽

2009 ◽

pp. 1-6 ◽

Cited By ~ 2

Author(s):

Gerd Ehret ◽

Michael Schulz ◽

Manuel Stavridis ◽

Clemens Elster

Keyword(s):

Measurement System ◽

Reference Measurement ◽

Reference Measurement System

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Evaluation of the clinical chemistry tests analytical performance by using different models and specifications

Turkish Journal of Biochemistry ◽

10.1515/tjb-2018-0250 ◽

2019 ◽

Vol 45 (1) ◽

pp. 11-18

Author(s):

Murat Keleş

Keyword(s):

Quality Management ◽

Measurement Uncertainty ◽

Goal Setting ◽

Clinical Chemistry ◽

Biological Variation ◽

Analytical Performance ◽

Analytical Quality ◽

Analytical Error ◽

Circular Letter ◽

Clinical Chemistry Tests

Abstract Background The importance of managing analytical quality in clinical laboratories is known. Goal-setting models are critical for analytical quality management, along with correctly implemented error models. However, the methods used to determine analytical performance and more importantly, the relevant analytical quality goals are open to discussion. Our aim was to compare the analytical performance characteristics of routine clinical chemistry tests with different goal-setting models which was proposed by various establishments. In addition, to provide a perspective to Turkish total analytical error (TAE) circular letter that compulsory to calculate from 2016. Materials and methods This study was performed by the data obtained from the internal and external quality control of clinical chemistry tests which were measured by Roche Cobas c501 biochemistry analyzer. TAE calculated with TAE% = 1.65 ×(CV%) + Bias% formula. Nordtest uncertainty model was used in the calculation of measurement uncertainty (MU). In this context, total analytical error was evaluated with biological variation (BV), RCPA, CLIA and Turkish allowable total error (ATE) goals. Measurement uncertainty was evaluated with only permissible measurement uncertainty (pU%) goal. Results In our study, RCPA goals are the most stringent, followed by the BVEuBIVAS, BVRicos, pU%, CLIA and finally the ATETurkey goals coming in last. In cumulatively, BVEuBIVAS goals were 18.3% lower than BVRicos for evaluated parameters. Conclusion The balance between applicability and analytical assurance of goals should be well ensured when determining goal-setting models. Circular letter (2016/18) creates awareness to the analytical quality management but still open to development. Biological variation dependent total allowable error model never designed to be used as benchmarks for measurement uncertainty and it is not methodologically appropriate for assessing measurement uncertainty which was estimated by the Nordtest method. Also considered that, the use of “permissible MU” is more methodologically appropriate in the evaluation of measurement uncertainty.

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Referenzmesssystem für dynamische Satellitennavigationsexperimente (Reference Measurement System for Dynamic Satellite Based Positioning Experiments)

tm - Technisches Messen ◽

10.1524/teme.2002.69.3.125 ◽

2002 ◽

Vol 69 (3/2002) ◽

Author(s):

L. Däubler ◽

B. Filova ◽

H. Schrom

Keyword(s):

Measurement System ◽

Reference Measurement ◽

Reference Measurement System

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New Reference Measurement System for Calibration of VLF High Voltage

IEEE Transactions on Instrumentation and Measurement ◽

10.1109/tim.2011.2108612 ◽

2011 ◽

Vol 60 (7) ◽

pp. 2422-2426 ◽

Cited By ~ 1

Author(s):

Sixten Bergman ◽

Anders Bergman

Keyword(s):

High Voltage ◽

Measurement System ◽

Reference Measurement ◽

Reference Measurement System

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Specifications for trueness and precision of a reference measurement system for serum/plasma 25-hydroxyvitamin D analysis

Clinica Chimica Acta ◽

10.1016/j.cca.2009.06.027 ◽

2009 ◽

Vol 408 (1-2) ◽

pp. 8-13 ◽

Cited By ~ 68

Author(s):

Dietmar Stöckl ◽

Patrick M. Sluss ◽

Linda M. Thienpont

Keyword(s):

Measurement System ◽

Reference Measurement ◽

Hydroxyvitamin D ◽

25 Hydroxyvitamin D ◽

Reference Measurement System

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PENETAPAN SISTEM ACUAN DAYA AC UNTUK LABORATORIUM STANDAR NASIONAL BERDASARKAN STANDARD WATT CONVERTER

Jurnal Standardisasi ◽

10.31153/js.v17i1.287 ◽

2016 ◽

Vol 17 (1) ◽

pp. 11

Author(s):

Agah Faisal

Keyword(s):

Measurement System ◽

Reference System ◽

Digital Voltmeter ◽

National Standard ◽

National Metrology Institute ◽

Standard Laboratory ◽

Reference Measurement ◽

Power Meter ◽

Ac Power ◽

Reference Measurement System

Abstrak Puslit KIM-LIPI telah mengembangkan suatu sistem pengukuran acuan daya AC untuk laboratorium standar nasional dengan ketelitian pengukuran yang lebih baik dari 75 ppm pada faktor cakupan 2 dan tingkat kepercayaan 95%. Sistem tersebut berbasis Standard Watt Converter (SWC), beban semu, dan digital DC voltmeter yang telah diketahui koreksinya melalui proses kalibrasi kepada standar yang dimiliki Lembaga Metrologi Nasional Australia (NMIA) dan Lembaga Metrologi Nasional Indonesia (Puslit KIM-LIPI). Metode perbandingan terhadap sistem acuan tersebut telah diterapkan pada suatu Unit Under Calibration (UUC) yang berupa power meter berketelitian tinggi. Hal ini dilakukan untuk menampilkan unjuk kerja sistem acuan daya AC dalam proses pengukuran koreksi pembacaan dari power meter. Hasil evaluasi pada titik-titik pengukuran 120 V, 5 A, dan 53 Hz menunjukkan bahwa koreksi pembacaan terbesar adalah 133 ppm. Nilai tersebut berkesesuian dengan kelas akurasi power meter ZERA RMM3001 yaitu 0,02% atau sebesar 200 ppm. Dari hasil unjuk kerja sistem pengukuran ini maka penetapan acuan daya AC untuk laboratorium standar nasional seperti Puslit KIM-LIPI mencukupi. Kata kunci: sistem pengukuran acuan, daya AC, standard watt converter, koreksi pembacaan, power meter. Abstract Puslit KIM-LIPI has developed an AC power reference measurement system for a national standard laboratory with a measurement precision better than 75 ppm at coverage factor 2 and confidence level 95 %. The system was based on the instruments of a standard watt converter, a phantom load, and a standard digital voltmeter, which the corrections of those readings are known by calibration processes to both National Metrology Institute of Australia (NMIA) and Puslit KIM-LIPI. The comparison method of the AC power reference system has been applied to the high precision power meter as a unit under calibration (UUC). This was done to show the measurement performance of AC power reference system in the process to find the reading correction of the power meter under calibration. The measurement evaluation at 120 V, 5 A, and 53 Hz showed that the worst reading correction was 133 ppm. That value was on the agreement with the class accuracy of ZERA RMM3001 power meter which is 0,02 % or 200 ppm. The performance of the measurement system indicated that the establishment of the ac power reference for a national standard laboratory such as Puslit KIM-LIPI was adequate. Keywords: reference measurement system, AC power, standard watt converter, reading correction, power meter.

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