Total error vs. measurement uncertainty: revolution or evolution?

2016 ◽  
Vol 54 (2) ◽  
Author(s):  
Wytze P. Oosterhuis ◽  
Elvar Theodorsson
Keyword(s):  
Clinical Chemistry ◽  
Total Error ◽  
Error Theory ◽  
Theory And Practice ◽  
Analytical Performance ◽  
Performance Goals ◽  
Comprehensive Overview ◽  
Medical Diagnoses ◽  
Stockholm Conference ◽  
Monitoring Treatment

AbstractThe first strategic EFLM conference “Defining analytical performance goals, 15 years after the Stockholm Conference” was held in the autumn of 2014 in Milan. It maintained the Stockholm 1999 hierarchy of performance goals but rearranged them and established five task and finish groups to work on topics related to analytical performance goals including one on the “total error” theory. Jim Westgard recently wrote a comprehensive overview of performance goals and of the total error theory critical of the results and intentions of the Milan 2014 conference. The “total error” theory originated by Jim Westgard and co-workers has a dominating influence on the theory and practice of clinical chemistry but is not accepted in other fields of metrology. The generally accepted uncertainty theory, however, suffers from complex mathematics and conceived impracticability in clinical chemistry. The pros and cons of the total error theory need to be debated, making way for methods that can incorporate all relevant causes of uncertainty when making medical diagnoses and monitoring treatment effects. This development should preferably proceed not as a revolution but as an evolution.

scholarly journals Performance Criteria for Testosterone Measurements Based on Biological Variation in Adult Males: Recommendations from the Partnership for the Accurate Testing of Hormones

2012 ◽  
Vol 58 (12) ◽  
pp. 1703-1710 ◽  
Author(s):  
Yeo-Min Yun ◽  
Julianne Cook Botelho ◽  
Donald W Chandler ◽  
Alex Katayev ◽  
William L Roberts ◽  
...  
Keyword(s):  
Total Error ◽  
Full Range ◽  
Biological Variation ◽  
Analytical Performance ◽  
Performance Criteria ◽  
Performance Goals ◽  
Adult Males ◽  
Large Variability ◽  
Wide Range ◽  
Variation Data

BACKGROUND Testosterone measurements that are accurate, reliable, and comparable across methodologies are crucial to improving public health. Current US Food and Drug Administration–cleared testosterone assays have important limitations. We sought to develop assay performance requirements on the basis of biological variation that allow physiologic changes to be distinguished from assay analytical errors. METHODS From literature review, the technical advisory subcommittee of the Partnership for the Accurate Testing of Hormones compiled a database of articles regarding analytical and biological variability of testosterone. These data, mostly from direct immunoassay-based methodologies, were used to specify analytical performance goals derived from within- and between-person variability of testosterone. RESULTS The allowable limits of desirable imprecision and bias on the basis of currently available biological variation data were 5.3% and 6.4%, respectively. The total error goal was 16.7%. From recent College of American Pathologists proficiency survey data, most currently available testosterone assays missed these analytical performance goals by wide margins. Data from the recently established CDC Hormone Standardization program showed that although the overall mean bias of selected certified assays was within 6.4%, individual sample measurements could show large variability in terms of precision, bias, and total error. CONCLUSIONS Because accurate measurement of testosterone across a wide range of concentrations [approximately 2–2000 ng/dL (0.069–69.4 nmol/L)] is important, we recommend using available data on biological variation to calculate performance criteria across the full range of expected values. Additional studies should be conducted to obtain biological variation data on testosterone from women and children, and revisions should be made to the analytical goals for these patient populations.

Optimizing the use of the “state-of-the-art” performance criteria

2015 ◽  
Vol 53 (6) ◽  
Author(s):  
Rainer Haeckel ◽  
Werner Wosniok ◽  
Thomas Streichert
Keyword(s):  
State Of The Art ◽  
Clinical Chemistry ◽  
Reference Interval ◽  
German Society ◽  
Laboratory Medicine ◽  
Biological Variation ◽  
The State ◽  
Analytical Performance ◽  
Performance Criteria ◽  
Performance Goals

AbstractThe organizers of the first EFLM Strategic Conference “Defining analytical performance goals” identified three models for defining analytical performance goals in laboratory medicine. Whereas the highest level of model 1 (outcome studies) is difficult to implement, the other levels are more or less based on subjective opinions of experts, with models 2 (based on biological variation) and 3 (defined by the state-of-the-art) being more objective. A working group of the German Society of Clinical Chemistry and Laboratory Medicine (DGKL) proposes a combination of models 2 and 3 to overcome some disadvantages inherent to both models. In the new model, the permissible imprecision is not defined as a constant proportion of biological variation but by a non-linear relationship between permissible analytical and biological variation. Furthermore, the permissible imprecision is referred to the target quantity value. The biological variation is derived from the reference interval, if appropriate, after logarithmic transformation of the reference limits.

The 1999 Stockholm Consensus Conference on quality specifications in laboratory medicine

2015 ◽  
Vol 53 (6) ◽  
Author(s):  
Callum G. Fraser
Keyword(s):  
Laboratory Medicine ◽  
Consensus Conference ◽  
Analytical Performance ◽  
Performance Goals ◽  
Analytical Quality ◽  
Global Consensus ◽  
Current State ◽  
Regulatory Bodies ◽  
Quality Specifications ◽  
Stockholm Conference

AbstractThe setting of analytical quality specifications in laboratory medicine has been a topic of discussion and debate for over 50 years: 15 years ago, as the subject matured and a profusion of recommendations appeared, many of them from expert groups, it was realised by a number of leading professionals that there was a need for a global consensus on the setting of such specifications. The Stockholm Conference held in 1999 on “Strategies to set global analytical quality specifications in laboratory medicine” achieved this and advocated the ubiquitous application of a hierarchical structure of approaches. The hierarchy has five levels, namely: 1) evaluation of the effect of analytical performance on clinical outcomes in specific clinical settings; 2) evaluation of the effect of analytical performance on clinical decisions in general using a) data based on components of biological variation, or b) analysis of clinicians’ opinions; 3) published professional recommendations from a) national and international expert bodies, or b) expert local groups or individuals; 4) performance goals set by a) regulatory bodies, or b) organisers of external quality assessment (EQA) schemes; and 5) goals based on the current state of the art as a) demonstrated by data from EQA or proficiency testing scheme, or b) found in current publications on methodology. This approach has been much used since its wide promulgation, but there have been ongoing criticisms and new developments. The time seems right for an objective reappraisal of recommended strategies to set analytical performance goals.

Performance goals for the laboratory testing of antithrombin, protein C and protein S

2006 ◽  
Vol 96 (11) ◽  
pp. 584-589 ◽  
Author(s):  
Frits Haverkate ◽  
Cornelis Kluft ◽  
Piet Meijer
Keyword(s):  
Protein C ◽  
Total Error ◽  
Diagnostic Testing ◽  
Protein S ◽  
Analytical Performance ◽  
Performance Goals ◽  
Analytical Quality ◽  
Performance Goal ◽  
Protein S Activity

SummaryTo achieve a reliable analytical quality for both monitoring and diagnostic testing, laboratories need to fulfil the widely accepted analytical performance goals based on the biological variation of the analytes of testing. Not only is the short-term analytical performance, which regularly is assessed by internal quality control procedures, of importance, but also the long-term analytical performance. To assess the long-term analytical performance, data obtained from an external quality assessment programme can be used. In this study we have used the evaluation model designed by the ECAT Foundation for the assessment of the longterm analytical performance, including imprecision, bias and total analytical error. The model was applied to the data from 136 different laboratories for the assay of antithrombin (activity), protein C (activity and antigen) and protein S (activity, total and free antigen). The imprecision (median; range), reflected by the long-term analytical coefficient of variation (LCVA), was the lowest for antithrombin (7.6%; 2.6 – 43.8%) and the highest for protein S activity (17.2%; 4.3 – 88.6%). For bias and total error the same pattern was observed (antithrombin: 3.8%; 0.3 – 17.1% and 9.1%; 3.4 – 34.3%, respectively; protein S activity: 12.8%; 3.1 – 34.8% and 24.5%; 9.9 – 87.0%, respectively). For the majority of the laboratories (70 – 85%) the imprecision contributes considerably more to the total error than the bias. However the effect of the bias on the analytical quality is not negligible. Assays for antithrombin, protein C and protein S are mainly used for diagnostic testing. About 70 – 100% of the laboratories can fulfil the desirable performance goal for imprecision. The desirable performance goal for bias was reached by 50 – 95% of the laboratories. In all cases the highest numbers of laboratories fulfilling performance goals was obtained for the protein C variables. To improve the analytical quality in assays of antithrombin, protein C and protein S it is highly recommended that primarily imprecision (non-systematic failures) be suppressed. However the effect of the bias (systematic failures) on the analytical quality should not be neglected. A useful tool for determining the imprecision (LCVA) and bias is the long-term analytical performance evaluation model as used by the ECAT Foundation.

Expressing analytical performance from multi-sample evaluation in laboratory EQA

2017 ◽  
Vol 55 (10) ◽  
Author(s):  
Marc H.M. Thelen ◽  
Rob T.P. Jansen ◽  
Cas W. Weykamp ◽  
Herman Steigstra ◽  
Ron Meijer ◽  
...  
Keyword(s):  
Quality Assessment ◽  
Clinical Chemistry ◽  
Total Error ◽  
Regression Line ◽  
Laboratory Medicine ◽  
Assessment System ◽  
Analytical Performance ◽  
European Federation ◽  
Laboratory Diagnostics ◽  
Tolerance Intervals

AbstractBackground:To provide its participants with an external quality assessment system (EQAS) that can be used to check trueness, the Dutch EQAS organizer, Organization for Quality Assessment of Laboratory Diagnostics (SKML), has innovated its general chemistry scheme over the last decade by introducing fresh frozen commutable samples whose values were assigned by Joint Committee for Traceability in Laboratory Medicine (JCTLM)-listed reference laboratories using reference methods where possible. Here we present some important innovations in our feedback reports that allow participants to judge whether their trueness and imprecision meet predefined analytical performance specifications.Methods:Sigma metrics are used to calculate performance indicators named ‘sigma values’. Tolerance intervals are based on both Total Error allowable (TEa) according to biological variation data and state of the art (SA) in line with the European Federation of Clinical Chemistry and Laboratory Medicine (EFLM) Milan consensus.Results:The existing SKML feedback reports that express trueness as the agreement between the regression line through the results of the last 12 months and the values obtained from reference laboratories and calculate imprecision from the residuals of the regression line are now enriched with sigma values calculated from the degree to which the combination of trueness and imprecision are within tolerance limits. The information and its conclusion to a simple two-point scoring system are also graphically represented in addition to the existing difference plot.Conclusions:By adding sigma metrics-based performance evaluation in relation to both TEa and SA tolerance intervals to its EQAS schemes, SKML provides its participants with a powerful and actionable check on accuracy.

scholarly journals Understanding the dimensions of managerial decency construct

2021 ◽  
Vol 26 (1) ◽  
pp. 37-62
Author(s):  
Belma Hadžiomerović ◽  
Emir Kurtić ◽  
Maja Arslanagić Kalajdžić
Keyword(s):  
Social Exchange ◽  
Social Exchange Theory ◽  
Employee Development ◽  
Theory And Practice ◽  
Measurement Scale ◽  
Mutual Trust ◽  
Comprehensive Overview ◽  
Qualitative And Quantitative ◽  
The Social ◽  
Insight Into

This study aims to improve the understanding of perceived managerial decency by developing an initial set of items for its measurement scale. Based on the social exchange theory and driven by the strong need for instilling more decency and civility in managerial discourse, this study makes a comprehensive overview of the scope and domain of perceived managerial decency and extracts the potential decency dimensions. After conducting a literature review, 50 collected interview responses on typical examples of managerial decency, as perceived by employees, served as a basis for further analysis. Using the content analysis tools, we generated a set of initial items and dimensions of decency. Those were further refined by 21 experts (5 from academia and 16 from the target audience) using the means of qualitative and quantitative assessment. as a result, we define the perceived managerial decency construct and outline its six potential dimensions: (1) respectful interactions, (2) treatment with good manners, (3) employee development, (4) mutual trust, (5) decent feedback, and (6) providing insight into a bigger picture, as well as generate a set of 75 valid items that reflect the decency construct. We further discuss the research implications for theory and practice.

scholarly journals Analytical Performance of 10 High-Volume Clinical Chemistry Assays on the Alinity c System

2018 ◽  
Vol 50 (1) ◽  
pp. e1-e8 ◽  
Author(s):  
Magdalena Krintus ◽  
Jon Ardanza Fernandez ◽  
Christine Chesters ◽  
Rossana Colla ◽  
Clare Ford ◽  
...  
Keyword(s):  
Clinical Chemistry ◽  
High Volume ◽  
Analytical Performance

Analytical performance goals for measuring prostate-specific antigen

1993 ◽  
Vol 39 (7) ◽  
pp. 1525-1529 ◽  
Author(s):  
H A Fritsche ◽  
R J Babaian
Keyword(s):  
Prostate Specific Antigen ◽  
Specific Antigen ◽  
Clinical Decision ◽  
Clinical Applications ◽  
Analytical Performance ◽  
Performance Goals ◽  
Clinical Use ◽  
Psa Test ◽  
Decision Points ◽  
Medical Relevance

Abstract We have assessed the feasibility of using fixed-limit criteria based on medical relevance and biological variation for evaluating the analytical performance of the prostate-specific antigen (PSA) test. The estimated within-subject variation of serum PSA is on the order of 10-20% at clinical decision points. The calculated performance goals of 5-10% CV are attainable with current immunoassay technology and agree with precision goals based on clinical experience and the current clinical use of the test. However, new clinical applications of PSA may require a degree of analytical performance that current methods may not be able to provide. The PSA model demonstrates the need for biologically based fixed-limit criteria for all tumor-marker tests.

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