An assessment of clinical laboratory performance for the determination of manganese in blood and urine

2016 ◽  
Vol 54 (12) ◽  
Author(s):  
Meredith L. Praamsma ◽  
Josiane Arnaud ◽  
David Bisson ◽  
Stuart Kerr ◽  
Chris F. Harrington ◽  
...  
Keyword(s):  
Characteristic Function ◽  
Clinical Laboratory ◽  
External Quality Assessment ◽  
Biological Variation ◽  
External Quality ◽  
Laboratory Performance ◽  
Quality Specifications ◽  
The Relationship ◽  
Mn Concentration

AbstractBackground:Proficiency testing or external quality assessment schemes (PT/EQASs) are an important method of assessing laboratory performance. As each scheme establishes assigned values and acceptable ranges for the analyte according to its own criteria, monitoring of participant performance varies according to the scheme and can lead to conflicting conclusions.Methods:Standard deviations (SDs) for PT were derived from Thompson’s and biological variation models applied to blood and urine manganese (Mn) robust data from four EQASs from North America and Europe. The fitness for purpose was verified by applying these SDs to individual results.Results:Using Thompson characteristic function the relationship between SD and Mn concentration, expressed in nmol/L was the square root of [19.7Conclusions:The biological variation model can be used to propose quality specifications for blood, however it could not be applied to urine. The Thompson characteristic function model could be applied to derive quality specifications for Mn in urine and, to a lesser extent in blood. The more lenient quality specifications for blood highlight the difficulty of determining Mn in this matrix. Further work is needed to harmonize PT, such as using assigned ranges for the specimens.

Thromboplastin Related Differences in the Determination of International Normalised Ratio: A Cause for Concern?

1994 ◽  
Vol 72 (03) ◽  
pp. 426-429 ◽  
Author(s):  
S Kitchen ◽  
I D Walker ◽  
T A L Woods ◽  
F E Preston
Keyword(s):  
Patient Management ◽  
External Quality Assessment ◽  
Oral Anticoagulant Therapy ◽  
Warfarin Dosage ◽  
External Quality ◽  
External Quality Assessment Scheme ◽  
International Normalised Ratio ◽  
The Uk ◽  
The Relationship

SummaryWhen the International Normalised Ratio (INR) is used for control of oral anticoagulant therapy the same result should be obtained irrespective of the laboratory reagent used. However, in the UK National External Quality Assessment Scheme (NEQAS) for Blood Coagulation INRs determined using different reagents have been significantly different.For 18 NEQAS samples Manchester Reagent (MR) was associated with significantly lower INRs than those obtained using Diagen Activated (DA, p = 0.0004) or Instrumentation Laboratory PT-Fib HS (IL, p = 0.0001). Mean INRs for this group were 3.15, 3.61, and 3.65 for MR, DA, and IL respectively. For 61 fresh samples from warfarin-ised patients with INRs of greater than 3.0 the relationship between thromboplastins in respect of INR was similar to that observed for NEQAS data. Thus INRs obtained with MR were significantly lower than with DA or IL (p <0.0001). Mean INRs for this group were 4.01, 4.40, and 4.59 for MR, DA, and IL respectively.We conclude that the differences between INRs measured with the thromboplastins studied here are sufficiently great to influence patient management through warfarin dosage schedules, particularly in the upper therapeutic range of INR. There is clearly a need to address the issues responsible for the observed discrepancies.

Combined international external quality assessment results of medical laboratory performance and reporting of samples with known antimicrobial resistance

Diagnosis ◽  
2018 ◽  
Vol 5 (3) ◽  
pp. 161-166
Author(s):  
Michael A. Noble ◽  
Robert Rennie
Keyword(s):  
Antimicrobial Resistance ◽  
Quality Assessment ◽  
Clinical Laboratory ◽  
External Quality Assessment ◽  
Medical Laboratory ◽  
External Quality ◽  
Laboratory Performance ◽  
Reporting Practices ◽  
Medical Laboratories ◽  
Poor Treatment

Abstract Background Reporting on the presence of antimicrobial resistance is of considerable concern both for individual patient care and for understanding the underlying health status within the community at large. Antimicrobial resistance is solely dependent upon clinical laboratory detection and thus can be impacted upon by the quality and competence of medical laboratories. Proficiency testing or external quality assessment (PT/EQA) is the international standard for the direct measurement of medical laboratory performance on critical testing. Methods An international, intercontinental collaborative retrospective study of medical laboratory performance in antibiotic resistance was performed by the Microbiology Working Group (MWG) of the European Organisation for External Quality Assurance for Laboratory Medicine (EQALM) with particular examination of laboratory performance on the testing and reporting of methicillin-resistant Staphylococcus aureus (MRSA), vancomycin-resistant enterococci (VRE) and carbapenem-resistant Enterobacteriaceae (CRE). Results The results of 1880 medical laboratories were compiled. Strictly accurate reporting of isolates as resistant occurred with MRSA 96.9%, with VRE 91.3% and with CRE 93.1% of the time. On the other hand, very major errors (reporting of false susceptibility) were observed with 2.2% of MRSA and 2.4% of VRE and 0.8% of CRE. Major errors (false resistance) were reported for vancomycin susceptibility testing for MRSA at a rate of 0.6%. Conclusions Depending on how clinical physicians read and understand microbiology susceptibility reports, proficient acceptable results were reported either between 91% and 94% of the time, or between 97% and 100%. While very major errors are infrequently reported, they were found in all regions and could potentially cause poor treatment decisions by clinicians. A collective analysis of multi-program PT/EQA information can provide valuable insights into the testing and reporting practices of medical laboratories.

scholarly journals Quality Specifications for the Determination of Copper, Zinc, and Selenium in Human Serum or Plasma: Evaluation of an Approach Based on Biological and Analytical Variation

2008 ◽  
Vol 54 (11) ◽  
pp. 1892-1899 ◽  
Author(s):  
Josiane Arnaud ◽  
Jean-Philippe Weber ◽  
Cas W Weykamp ◽  
Patrick J Parsons ◽  
Jurgen Angerer ◽  
...  
Keyword(s):  
Quality Assessment ◽  
Trace Element ◽  
Interindividual Variability ◽  
External Quality Assessment ◽  
Serum Copper ◽  
External Quality ◽  
Target Concentration ◽  
Quality Specifications ◽  
Copper Zinc

Abstract Background: Trace element external quality assessment schemes monitor laboratory performance and provide a stimulus for improvement in accuracy. However, monitoring of participant performance varies according to the scheme and can lead to conflicting conclusions. Methods: Quality specifications based on biological intra- and interindividual variability were calculated and compared to those currently used by various trace element external quality assessment schemes for plasma or serum copper, zinc, and selenium concentrations. For this purpose, we evaluated results reported by participating laboratories in different schemes, at key concentrations, using z scores. Results: Minimal quality specifications developed from the biological intra- and interindividual variability were, for Cu, ±0.84 μmol/L or 12% of the assigned target concentration, whichever is greater; for Zn, ±1.20 μmol/L or 15% of the assigned target concentration, whichever is greater; and for Se, ±0.072 μmol/L or 12% of the assigned target concentration, whichever is greater. Reported performance of the participating laboratories depended on analyte, concentration, and the selected quality specification. In addition, the most commonly used methods for the determination of Cu, Zn, and Se may give different results. Conclusions: The proposed minimal quality specifications based on biological variation are generally slightly less stringent than those currently in use, although they do not drastically change the performance evaluation in the different schemes. These specifications are a first step in the harmonization of practices among the schemes and remain to be evaluated.

scholarly journals Comparison of Procedures for Evaluating Laboratory Performance in External Quality Assessment Schemes for Lead in Blood and Aluminum in Serum Demonstrates the Need for Common Quality Specifications

2002 ◽  
Vol 48 (11) ◽  
pp. 2000-2007 ◽  
Author(s):  
Andrew Taylor ◽  
Jurgen Angerer ◽  
Francoise Claeys ◽  
Jesper Kristiansen ◽  
Olav Mazarrasa ◽  
...  
Keyword(s):  
Quality Assessment ◽  
External Quality Assessment ◽  
Total Error ◽  
Blood Lead ◽  
External Quality ◽  
Target Concentration ◽  
Laboratory Performance ◽  
Environmental Laboratory ◽  
Z Scores ◽  
Quality Specifications

Abstract Background: The different scoring methods used by eight European External Quality Assessment Schemes (EQASs) for occupational and environmental laboratory medicine were compared to develop suitable quality specifications as a step toward harmonization. Methods: Real results for blood lead and serum aluminum assays, reported by participants in Italian and United Kingdom EQASs, were evaluated according to individual scheme scoring criteria. The same results were then used to produce z scores using scheme-based between-laboratory SDs as the estimate of variability to determine whether simple performance-derived quality specifications produced better agreement among schemes. Results: The schemes gave conflicting assessments of participants’ performance, and participants judged to be successful by one scheme could be defined as performing inadequately by another. An approach proposed by Kenny et al. (Scand J Clin Lab Invest 1999;59:585), which uses clinical inputs to set targets for analytical imprecision, bias, and total error allowable, was then used to elaborate quality specifications. Conclusions: We suggest that the CLIA ′88 recommendations for blood lead (± 40 μg/L or ± 10% of the target concentration, whichever is the greater) could be used as a quality specification, although a revision to ± 30 μg/L or ± 10% is recommended. For serum aluminum, a suitable quality specification of ± 5 μg/L or ± 20% of the target concentration, whichever is the greater, is suggested. These specifications may be used to compare laboratory performance across schemes.

scholarly journals Diagnostic Challenges on the Laboratory Detection of Lupus Anticoagulant

Biomedicines ◽  
2021 ◽  
Vol 9 (7) ◽  
pp. 844
Author(s):  
Armando Tripodi
Keyword(s):  
Lupus Anticoagulant ◽  
Clinical Laboratory ◽  
External Quality Assessment ◽  
State Of The Art ◽  
Diagnostic Procedures ◽  
External Quality ◽  
Glycoprotein I ◽  
Current State ◽  
Clinical Laboratories

Lupus anticoagulant (LA) is one of the three laboratory parameters (the others being antibodies to either cardiolipin or β2-glycoprotein I) which defines the rare but potentially devastating condition known as antiphospholipid syndrome (APS). Testing for LA is a challenging task for the clinical laboratory because specific tests for its detection are not available. However, proper LA detection is paramount for patients’ management, as its persistent positivity in the presence of (previous or current) thrombotic events, candidate for long term anticoagulation. Guidelines for LA detection have been established and updated over the last two decades. Implementation of these guidelines across laboratories and participation to external quality assessment schemes are required to help standardize the diagnostic procedures and help clinicians for appropriate management of APS. This article aims to review the current state of the art and the challenges that clinical laboratories incur in the detection of LA.

scholarly journals External Quality Assessment for the Determination of Diphtheria Antitoxin in Human Serum

2010 ◽  
Vol 17 (8) ◽  
pp. 1282-1290 ◽  
Author(s):  
Paolo Di Giovine ◽  
Antonella Pinto ◽  
Rose-Marie Ölander ◽  
Dorothea Sesardic ◽  
Paul Stickings ◽  
...  
Keyword(s):  
Quality Assessment ◽  
External Quality Assessment ◽  
Accurate Determination ◽  
Enzyme Linked Immunosorbent Assay ◽  
Reference Laboratory ◽  
Routine Method ◽  
External Quality ◽  
Passive Hemagglutination

ABSTRACT Accurate determination of diphtheria toxin antibodies is of value in determining the rates of immunity within broad populations or the immune status of individuals who may be at risk of infection, by assessing responses to vaccination and immunization schedule efficacy. Here we report the results of an external quality assessment (EQA) study for diphtheria serology, performed within the dedicated surveillance network DIPNET. Twelve national laboratories from 11 European countries participated by testing a standard panel of 150 sera using their current routine method: Vero cell neutralization test (NT), double-antigen enzyme-linked immunosorbent assay (ELISA; DAE), dual double-antigen time-resolved fluorescence immunoassay (dDA-DELFIA), passive hemagglutination assay (PHA), toxin binding inhibition assay (ToBI), and in-house or commercial ELISAs. The objective of the study was not to identify the best assay, as the advantages and drawbacks of methods used were known, but to verify if laboratories using their routine method would have categorized (as negative, equivocal, or positive) a serum sample in the same way. The performance of each laboratory was determined by comparing its results on a quantitative and qualitative basis to NT results from a single reference laboratory, as this test is considered the in vitro “gold standard.” The performance of laboratories using NT was generally very good, while the laboratories’ performance using other in vitro methods was variable. Laboratories using ELISA and PHA performed less well than those using DAE, dDA-DELFIA, or ToBI. EQA is important for both laboratories that use in vitro nonstandardized methods and those that use commercial ELISA kits.

Assessment of the correctness of identification and determination of antimicrobial susceptibility of Streptococcus pneumoniae in microbiological laboratories in Poland

2020 ◽  
Vol 55 (4) ◽  
pp. 271-276
Author(s):  
Ewa Młodzińska ◽  
Waleria Hryniewicz
Keyword(s):  
Quality Control ◽  
Antimicrobial Susceptibility ◽  
Bacterial Resistance ◽  
External Quality Assessment ◽  
Resistance Mechanisms ◽  
Medical Problems ◽  
External Quality ◽  
External Quality Assessment Scheme ◽  
Reliable Identification

The increase in bacterial resistance to antimicrobials is one of the most serious medical problems, therefore reliable identification in microbiological laboratories is important. The Polish National External Quality Assessment Scheme in Microbiological Diagnostics – POLMICRO programme is organized by the Centre of Quality Control in Microbiology (CQCM) enables the assessment of the competence of Polish microbiological laboratories in the field of identification, determination of susceptibility and detection of drug resistance mechanisms. This work presents the assessment of the results of identification and determination of S. pneumoniae antimicrobial susceptibility obtained by Polish laboratories during the 20 years of experience of the POLMICRO programme.

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