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.

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

1993 ◽  
Vol 39 (6) ◽  
pp. 1001-1006 ◽  
Author(s):  
L M Thienpont ◽  
A P Leenheer ◽  
D Stöckl ◽  
H Reinauer
Keyword(s):  
Uric Acid ◽  
Linear Regression Analysis ◽  
Gas Chromatography Mass Spectrometry ◽  
Accuracy Control ◽  
Self Evaluation ◽  
Method Transfer ◽  
Reference Methods ◽  
Target Values ◽  
General Reliability ◽  
Student’S T

Abstract We describe the testing of transferability of candidate Reference Methods developed by INSTAND for cholesterol, creatinine, uric acid, and glucose. The methods are based on isotope dilution-gas chromatography--mass spectrometry. The study consisted of two parts: setup of the methods and self-evaluation for readiness in the collaborating laboratory, followed by independent measurements in parallel with INSTAND. Criteria used for judging the transferability and general reliability of the candidate Reference Methods were: the accuracy and precision of the collaborating laboratory and the agreement between the two laboratories. The accuracy was judged from the results on the Standard Reference Material 909 from the National Institute of Standards and Technology. For all analytes except glucose the bias from the certified value was < 0.7%. The mean intralaboratory imprecision ranged from 0.66% to 1.24%. The agreement between the results was tested by an advanced linear-regression analysis and Student's t-test. In general, the results demonstrate that the candidate Reference Methods developed by INSTAND can be successfully transferred without loss of their inherent precision and accuracy.

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.

Commutability of external quality assessment materials for serum sodium and potassium measurements

2019 ◽  
Vol 57 (4) ◽  
pp. 465-475 ◽  
Author(s):  
Ying Yan ◽  
Bingqing Han ◽  
Haijian Zhao ◽  
Rong Ma ◽  
Jing Wang ◽  
...  
Keyword(s):  
Quality Assessment ◽  
Serum Sodium ◽  
Inductively Coupled Plasma ◽  
External Quality Assessment ◽  
External Quality ◽  
Inductively Coupled ◽  
Evaluation Approach ◽  
Reference Methods ◽  
Plasma Mass Spectrometry ◽  
Sodium And Potassium

Abstract Background The commutability of electrolyte trueness verification materials (ETVs) and commercial general chemistry materials (GCs) was evaluated to investigate their suitability for use in an external quality assessment (EQA) program for serum sodium and potassium measurements. Methods Eighty fresh individual human samples (40 for sodium measurements and 40 for potassium measurements), six ETVs and three GCs were analyzed by five routine methods (validated methods) and by inductively coupled plasma mass spectrometry reference methods (comparative methods) for the determination of sodium and potassium. The commutability was analyzed according to Clinical and Laboratory Standards Institute (CLSI) EP14-A3 protocol and difference in bias approach, respectively. The linearity, bias and imprecision of the routine methods were also assessed according to CLSI guidelines. Results According to EP14-A3 protocol, ETVs were commutable for all assays, and GCs were commutable for 3/5 assays for sodium. ETVs were commutable in most assays except Cobas C501, while GCs showed no commutability except in case of AU5821 for potassium. According to a difference in bias approach, the commutability of ETVs was inconclusive for most routine assays for both sodium and potassium, and GCs were inconclusive for sodium and non-commutable for potassium in most routine assays. The routine methods exhibited excellent linearities and precisions. The majority and minority of relative biases between the routine and reference methods were beyond the bias limits for sodium and potassium, respectively. Conclusions Superiority in the commutability of ETVs over GCs was observed among the sodium and potassium assays whichever evaluation approach was applied.

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.

National External Quality Assessment follow-up: 2010–2017 Turkish experience

2019 ◽  
Vol 44 (1) ◽  
pp. 1-8 ◽  
Author(s):  
Ferzane Mercan ◽  
Muhittin A. Serdar ◽  
Mehmet Senes ◽  
Dildar Konukoglu ◽  
Tamer Cevat İnal ◽  
...  
Keyword(s):  
Quality Assessment ◽  
External Quality Assessment ◽  
Total Error ◽  
Data Entry ◽  
Error Rates ◽  
Performance Ratio ◽  
External Quality ◽  
Significant Discrepancy ◽  
Technical Problems

Abstract Objective Medical laboratories encounter critical obstacles in External Quality Assessment (EQA) practices that are key to assessment of the analytical period. Present study aims to unveil the challenges in nationwide inter-laboratory harmonization and suggest practical solutions. Materials and methods EQA results of 1941 laboratories participating in 18 different EQA-programs between 2010 and 2017 were examined. Standard Deviation Index (SDI) of each program calculated using 801,028 sample data from 24 different clinical chemical tests were used to conduct a process assessment. Results There is a significant discrepancy in unsatisfactory performance ratio among different EAQ-programs with an average of 3.4% (27,074 cases) between 2010 and 2017 and a decreasing trend (~40–50%) in 7-years. Programs with higher SDI display lower discrepancy rates. Reasons for unaccepted results appear to be data entry errors (8.27–22.2%), material dilution errors (5–11.4%), technical problems (3.76–7.9%); while random or unidentified causes account for a major of 44.9–59.5%. In 7-years, 15.7% reduction was observed in average SDI of all tests. Conclusion With the launch of national EQA follow-up program, increased awareness of the analytical processes led to a decrease in unaccepted results and variances in the analytical period. Staff training is suggested as a significant measure. In addition, simultaneous assessment of SDI and allowable total error rates would reduce the variation between programs.

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