Specimen materials, target values and commutability for external quality assessment (proficiency testing) schemes

2003 ◽  
Vol 327 (1-2) ◽  
pp. 25-37 ◽  
Author(s):  
W.Greg Miller
Keyword(s):  
Quality Assessment ◽  
Proficiency Testing ◽  
External Quality Assessment ◽  
External Quality ◽  
Proficiency Testing Schemes ◽  
Target Values

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.

Establishing an Accuracy Basis for the Vitamin D External Quality Assessment Scheme (DEQAS)

2017 ◽  
Vol 100 (5) ◽  
pp. 1277-1287 ◽  
Author(s):  
Carolyn Q Burdette ◽  
Johanna E Camara ◽  
Federica Nalin ◽  
Jeanita Pritchett ◽  
Lane C Sander ◽  
...  
Keyword(s):  
Vitamin D ◽  
Quality Assessment ◽  
External Quality Assessment ◽  
Measurement Procedure ◽  
Binding Assays ◽  
External Quality ◽  
External Quality Assessment Scheme ◽  
Hydroxyvitamin D ◽  
Target Values ◽  
High Concentrations

Abstract Until recently, the Vitamin D External Quality Assessment Scheme (DEQAS) assessed the performance of various assays for the determination of serum total 25-hydroxyvitamin D [25(OH)D] by using a consensus mean based on the all-laboratory trimmed mean (ALTM) of the approximately 1000 participants' results. Since October 2012, the National Institute of Standardsand Technology (NIST), as part of the Vitamin D Standardization Program, has participated in DEQAS by analyzing the quarterly serum sample sets using an isotope dilution LC-tandem MS (ID LC-MS/MS) reference measurement procedure to assign an accuracy-based target value for serum total 25(OH)D. NIST has analyzed90 DEQAS samples (18 exercises × 5 samples/exercise) to assign target values. The NIST-assigned values are compared with the ALTM and the biases assessed for various assays used by the participants, e.g., LC-MS/MS, HPLC, and several ligand-binding assays. The NIST-value assignment process and the resultsof the analyses of the 90 DEQAS samples are summarized. The absolute mean bias between the NIST-assignedvalues and the ALTM was 5.6%, with 10% of the samples having biases >10%. Benefits of the accuracy-based target values are presented, including for sample sets with high concentrations of 25(OH)D2 and 3-epi-25(OH)D3.

Assessing quality on the Sigma scale from proficiency testing and external quality assessment surveys

2015 ◽  
Vol 53 (10) ◽  
Author(s):  
James O. Westgard ◽  
Sten A. Westgard
Keyword(s):  
Quality Assessment ◽  
Proficiency Testing ◽  
External Quality Assessment ◽  
Objective Assessment ◽  
Analytical Quality ◽  
External Quality ◽  
Proficiency Assessment ◽  
Laboratory Examinations ◽  
Intended Use

AbstractThere is a need to assess the quality being achieved for laboratory examinations that are being utilized to support evidence-based clinical guidelines. Application of Six Sigma concepts and metrics can provide an objective assessment of the current analytical quality of different examination procedures.A “Sigma Proficiency Assessment Chart” can be constructed for data obtained from proficiency testing and external quality assessment surveys to evaluate the observed imprecision and bias of method subgroups and determine quality on the Sigma scale.Data for hemoglobin AAssessment of quality on the Sigma scale provides evidence of the analytical performance that is being achieved relative to requirements for intended use and should be useful for identifying and prioritizing improvements that are needed in the analytical quality of laboratory examinations. In spite of global and national standardization programs, bias is still a critical limitation of current HbA

scholarly journals Proficiency Testing/External Quality Assessment: Current Challenges and Future Directions

2011 ◽  
Vol 57 (12) ◽  
pp. 1670-1680 ◽  
Author(s):  
W Greg Miller ◽  
Graham RD Jones ◽  
Gary L Horowitz ◽  
Cas Weykamp
Keyword(s):  
Quality Assessment ◽  
Proficiency Testing ◽  
External Quality Assessment ◽  
Peer Group ◽  
Measurement Procedure ◽  
Comparison Method ◽  
External Quality ◽  
Group Evaluation ◽  
The Status ◽  
Relationship Of

BACKGROUND Proficiency testing (PT), or external quality assessment (EQA), is intended to verify on a recurring basis that laboratory results conform to expectations for the quality required for patient care. CONTENT Key factors for interpreting PT/EQA results are knowledge of the commutability of the samples used and the process used for target value assignment. A commutable PT/EQA sample demonstrates the same numeric relationship between different measurement procedures as that expected for patients' samples. Noncommutable PT/EQA samples frequently have a matrix-related bias of unknown magnitude that limits interpretation of results. PT/EQA results for commutable samples can be used to assess accuracy against a reference measurement procedure or a designated comparison method. In addition, the agreement of the results between different measurement procedures for commutable samples reflects that which would be seen for patients' samples. PT/EQA results for noncommutable samples must be compared to a peer group mean/median of results from participants who use measurement procedures that are expected to have the same or very similar matrix-related bias. Peer group evaluation is used to asses whether a laboratory is using a measurement procedure in conformance to the manufacturer's specifications and/or in conformance to other laboratories using the same technology. A noncommutable PT/EQA sample does not give meaningful information about the relationship of results for patients' samples between different measurement procedures. SUMMARY PT/EQA provides substantial value to the practice of laboratory medicine by assessing the performance of individual laboratories and, when commutable samples are used, the status of standardization or harmonization among different measurement procedures.

scholarly journals The results of external quality assessment programme on urine leukocyte and erythrocyte counting in Poland

2020 ◽  
Vol 30 (2) ◽  
pp. 278-286
Author(s):  
Agnieszka Ćwiklińska ◽  
Barbara Kortas-Stempak ◽  
Maciej Jankowski ◽  
Gabriela Bednarczuk ◽  
Aleksandra Fijałkowska ◽  
...  
Keyword(s):  
Quality Assessment ◽  
External Quality Assessment ◽  
Particle Analysis ◽  
External Quality ◽  
Automated Method ◽  
Percentage Difference ◽  
Target Values ◽  
Important Diagnostic Tool ◽  
Manual Methods

Introduction: Urine particle analysis is an important diagnostic tool. The aim of this study was to evaluate the quality of urine leukocyte (WBC) and erythrocyte (RBC) counting results obtained with manual and automated methods in Polish laboratories participating in the international external quality assessment (EQA) programme. Materials and methods: 1400 WBC and RBC counting results were obtained from 183 laboratories in EQA surveys organised by Labquality (Helsinki, Finland) from 2017 to 2019. The between-laboratory coefficient of variation (CV), the percentage difference between the laboratories' results and target values (Q-score (%)), as well as modified Youden plots were analysed. Results: For automated method groups, the medians of inter-laboratory CVs varied from 14% to 33% for WBC counting and from 10% to 39% for RBC counting. For manual method groups, the medians of CV varied from 53% to 71% (WBC) and from 55% to 70% (RBC), and they were significantly higher, in comparison to CVs for most automated method groups (P < 0.001). The highest percentage of results outside the target limits (36%) and the highest range of Q-score (%) (from - 93% to 706%) were observed for laboratories which participated in the surveys for the first or second time. The percentage of deviating results and the ranges of Q-score decreased with an increased frequency of laboratories’ participation in the surveys. Conclusions: The quality of manual methods of urine WBC and RBC counting is unsatisfactory. There is an urgent need to take actions to improve laboratories’ performance and to increase harmonisation of the results.

Candidate reference methods for determining target values for cholesterol, creatinine, uric acid, and glucose in external quality assessment and internal accuracy control. I. Method setup

1993 ◽  
Vol 39 (6) ◽  
pp. 993-1000 ◽  
Author(s):  
D Stöckl ◽  
H Reinauer
Keyword(s):  
Uric Acid ◽  
Quality Assessment ◽  
External Quality Assessment ◽  
Total Error ◽  
Reference Method ◽  
Gas Chromatography Mass Spectrometry ◽  
Accuracy Control ◽  
External Quality ◽  
Reference Methods ◽  
Target Values

Abstract In Germany, the target values for External Quality Assessment (EQA) and internal accuracy control are determined by Reference Methods for several analytes, including cholesterol, creatinine, uric acid, and glucose. We present candidate Reference Methods for these compounds, based on isotope dilution-gas chromatography--mass spectrometry methods that have been developed at INSTAND, one of the two official Germany EQA reference institutions. Each Reference Method target value is calculated from six independent measurements performed on three different days. The mean method CVs ranged from 0.66% for glucose to 0.96% for creatinine. The inaccuracy (bias) of the methods is < 0.7%, as compared with the Standard Reference Material 909 of the National Institute of Standards and Technology. The maximum total error of a Reference Method value, including the 95% confidence interval and systematic errors, is < 2.3%. The presented candidate Reference Methods have been successfully used to set target values in the German EQA scheme and the internal accuracy control of routine laboratories.

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