scholarly journals Effect of Bilirubin on Uricase-Peroxidase Coupled Reactions. Implications for Urate Measurement in Clinical Samples and External Quality Assessment Schemes

1991 ◽  
Vol 28 (1) ◽  
pp. 98-100 ◽  
Author(s):  
D. A. Hullin ◽  
M. T. G. McGrane
Keyword(s):  
Quality Assessment ◽  
External Quality Assessment ◽  
Clinical Samples ◽  
External Quality ◽  
Coupled Reactions

Evaluation of the ARKRAY HA-8190V instrument for HbA1c

2020 ◽  
Vol 0 (0) ◽  
Author(s):  
Eline A.E. van der Hagen ◽  
Sanne Leppink ◽  
Karin Bokkers ◽  
Carla Siebelder ◽  
Cas W. Weykamp
Keyword(s):  
Quality Assessment ◽  
Concentration Level ◽  
External Quality Assessment ◽  
Clinical Samples ◽  
Diabetic Patients ◽  
External Quality ◽  
Target Values ◽  
Performance Specifications ◽  
Certification Programme ◽  
And Performance

Abstract Objectives Hemoglobin A1c (HbA1c) is a valuable parameter in the monitoring of diabetic patients and increasingly in diagnosis of diabetes. Manufacturers continuously optimize instruments, currently the main focus is to achieve faster turnaround times. It is important that performance specifications remain of high enough standard, which is evaluated in this study for the new ARKRAY HA-8190V instrument. Methods The Clinical and Laboratory Standards Institute (CLSI) protocols EP-5, EP-9 and EP-10 were applied to investigate imprecision, bias and linearity. In addition potential interferences, performance in External Quality Assessment (EQA) and performance against the HA-8180V instrument in 220 clinical samples was evaluated. Results The HA-8190V demonstrates a CV of ≤0.8% in IFCC SI units (≤0.6% National Glycohemoglobin Standardization Program [NGSP]) at 34 and 102 mmol/mol levels (5.3 and 11.5% NGSP) and a bias of −0.1 mmol/mol (−0.01% NGSP) at a concentration of 50 mmol/mol (6.7% NGSP), but with a significant slope as compared to target values. This results in a bias of −1.0 and 0.9 mmol/mol (−2.0 and 0.9% NGSP) at the 30 and 70 mmol/mol (4.9 and 8.6% NGSP) concentration level. Simulation of participation in the IFCC certification programme results in a Silver score (bias −0.1 mmol/mol, CV 1.1%). Interference in the presence of the most important Hb variants (AS, AC, AE, AD) and elevated HbA2 and HbF concentrations is less than 3 mmol/mol (0.3% NGSP) at a concentration of 50 mmol/mol (6.7% NGSP). Conclusions Analytical performance of the HA-8190V is very good, especially with respect to precision and HbA1c quantification in the presence of the most common Hb variants.

scholarly journals IFCC Working Group Recommendations for Assessing Commutability Part 2: Using the Difference in Bias between a Reference Material and Clinical Samples

2018 ◽  
Vol 64 (3) ◽  
pp. 455-464 ◽  
Author(s):  
Göran Nilsson ◽  
Jeffrey R Budd ◽  
Neil Greenberg ◽  
Vincent Delatour ◽  
Robert Rej ◽  
...  
Keyword(s):  
Reference Material ◽  
Quality Assessment ◽  
Working Group ◽  
External Quality Assessment ◽  
Clinical Samples ◽  
External Quality ◽  
Amount Of Substance ◽  
Specific Effects ◽  
Fit For Purpose ◽  
The Difference

Abstract A process is described to assess the commutability of a reference material (RM) intended for use as a calibrator, trueness control, or external quality assessment sample based on the difference in bias between an RM and clinical samples (CSs) measured using 2 different measurement procedures (MPs). This difference in bias is compared with a criterion based on a medically relevant difference between an RM and CS results to make a conclusion regarding commutability. When more than 2 MPs are included, the commutability is assessed pairwise for all combinations of 2 MPs. This approach allows the same criterion to be used for all combinations of MPs included in the assessment. The assessment is based on an error model that allows estimation of various random and systematic sources of error, including those from sample-specific effects of interfering substances. An advantage of this approach is that the difference in bias between an RM and the average bias of CSs at the concentration (i.e., amount of substance present or quantity value) of the RM is determined and its uncertainty estimated. An RM is considered fit for purpose for those MPs for which commutability is demonstrated.

scholarly journals External Quality Assessment of Techniques for the Detection of Drugs of Abuse in Urine

1994 ◽  
Vol 31 (4) ◽  
pp. 335-342 ◽  
Author(s):  
J F Wilson ◽  
B L Smith ◽  
P A Toseland ◽  
J Williams ◽  
D Burnett ◽  
...  
Keyword(s):  
Quality Assessment ◽  
High Performance ◽  
Drugs Of Abuse ◽  
External Quality Assessment ◽  
Cross Reactivity ◽  
Clinical Samples ◽  
External Quality ◽  
True Negative ◽  
External Quality Assessment Scheme ◽  
The Uk

Five chromatographic and six immunoassay techniques were compared using data reported by 131 participants in the UK National External Quality Assessment Scheme for Drugs of Abuse in Urine. Twenty Five samples were studied containing none or one of three concentrations of amphetamine, barbiturates, benzodiazepines, benzoylecgonine, methadone and morphine. Technique sensitivity and specificity achieved with realistic clinical samples of 25 mL vol were assessed as the percentage of true positive and true negative tests, respectively. Thin-layer chromatography was inadequate for the detection of several analytes, the sensitivity for 0 · 5 mg/L of benzoylecgonine being < 30%, and for 1 · 5 mg/L of amphetamine < 86%. Gas chromatography with mass spectrometry was significantly less sensitive than other techniques for the detection of 0·5 mg/L of benzoylecgonine (71%) and 1 · 5 mg/L of morphine (88%). High-performance liquid chromatography was the most sensitive for amphetamine. Immunoassays performed well when operating above then-specified cut-off concentrations but, because they are directed to quinalbarbitone showed reduced cross-reactivity with amylobarbitone, the barbiturate more commonly prescribed in the UK.

scholarly journals Comparability of thyroid-stimulating hormone immunoassays using fresh frozen human sera and external quality assessment data

PLoS ONE ◽  
2021 ◽  
Vol 16 (6) ◽  
pp. e0253324
Author(s):  
Shunli Zhang ◽  
Fei Cheng ◽  
Hua Wang ◽  
Jiangping Wen ◽  
Jie Zeng ◽  
...  
Keyword(s):  
Quality Assessment ◽  
Human Serum ◽  
External Quality Assessment ◽  
Thyroid Stimulating Hormone ◽  
Clinical Samples ◽  
Systematic Bias ◽  
Serum Samples ◽  
Bias Analysis ◽  
External Quality ◽  
Human Sera

Background This study aimed to assess the comparability among assays using freshly frozen human sera and external quality assessment (EQA) data in China. Methods Twenty-nine serum samples and two commercial EQA materials, obtained from the National Center for Clinical Laboratories (NCCL), were analyzed in triplicate using eight routine TSH assays. The commutability of commercial EQA materials (NCCL materials) was evaluated in accordance with the CLSI EP30-A and IFCC bias analysis. Median values obtained for the NCCL EQA materials were used to determine the systematic and commutability-related biases among immunoassays through back-calculation. The comparability of TSH measurements from a panel of clinical samples and NCCL EQA data was determined on the basis of Passing–Bablok regression. Furthermore, human serum pools were used to perform commutable EQA. Results NCCL EQA materials displayed commutability among three or five of seven assay combinations according CLSI or IFCC approach, respectively. The mean of systematic bias ranged from -13.78% to 9.85% for the eight routine TSH assays. After correcting for systematic bias, averaged commutability-related biases ranged between -42.26% and 12.19%. After correction for systematic and commutability -related biases, the slopes indicating interassay relatedness ranged from 0.801 to 1.299 using individual human sera, from 0.735 to 1.254 using NCCL EQA data, and from 0.729 to 1.115 using pooled human serum EQA(the commutable EQA). Conclusions The harmonization of TSH measurement is challenging; hence, systematic and commutability-related biases should be determined and corrected for accurate comparisons among assays when using human individual serum and the commercial EQA materials.

scholarly journals The versatility of external quality assessment for the surveillance of laboratory and in vitro diagnostic performance: SARS-CoV-2 viral genome detection in Austria

2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Christoph Buchta ◽  
Jeremy V. Camp ◽  
Jovana Jovanovic ◽  
Peter Chiba ◽  
Elisabeth Puchhammer-Stöckl ◽  
...  
Keyword(s):  
Quality Assessment ◽  
External Quality Assessment ◽  
False Negative ◽  
Positive Sample ◽  
Performance Criteria ◽  
External Quality ◽  
Assay Sensitivity ◽  
Dilution Series ◽  
Test Systems

Abstract Objectives External quality assessment (EQA) schemes provide information on individual and general analytical performance of participating laboratories and test systems. The aim of this study was to investigate the use and performance of SARS-CoV-2 virus genome detection systems in Austrian laboratories and their preparedness to face challenges associated with the pandemic. Methods Seven samples were selected to evaluate performance and estimate variability of reported results. Notably, a dilution series was included in the panel as a measure of reproducibility and sensitivity. Several performance criteria were evaluated for individual participants as well as in the cohort of all participants. Results A total of 109 laboratories participated and used 134 platforms, including 67 different combinations of extraction and PCR platforms and corresponding reagents. There were no false positives and 10 (1.2%) false negative results, including nine in the weakly positive sample (C t ∼35.9, ∼640 copies/mL). Twenty (22%) laboratories reported results of mutation detection. Twenty-five (19%) test systems included amplification of human RNA as evidence of proper sampling. The overall linearity of C t values from individual test systems for the dilution series was good, but inter-assay variability was high. Both operator-related and systematic failures appear to have caused incorrect results. Conclusions Beyond providing certification for participating laboratories, EQA provides the opportunity for participants to evaluate their performance against others so that they may improve operating procedures and test systems. Well-selected EQA samples offer additional inferences to be made about assay sensitivity and reproducibility, which have practical applications.

Commutability of possible external quality assessment materials for progesterone measurement

2021 ◽  
Vol 87 ◽  
pp. 39-45
Author(s):  
Xilian Yi ◽  
Yufei Wang ◽  
Tianjiao Zhang ◽  
Jie Zeng ◽  
Haijian Zhao ◽  
...  
Keyword(s):  
Quality Assessment ◽  
External Quality Assessment ◽  
External Quality
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