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Mosca A.,University of Milan | Paleari R.,University of Milan | Carobene A.,Laboratorio Of Standardizzazione | Weykamp C.,Location Queen Beatrix Hospital | And 2 more authors.
Clinica Chimica Acta | Year: 2015

Background: The determination of glycated hemoglobin is a key indicator for the management of diabetic patients. A reference measurement system for its determination is available and IVD manufacturers should have aligned their assay to this system. Methods: Two fresh blood sampleswere distributed by courier to 206 Italian laboratories asking for the determination of their HbA1c concentration. Target HbA1c values were assigned by the IFCC reference measurement procedure. Results: From 193 laboratories using analytical systems from five manufacturers (Bio-Rad Laboratories, A. Menarini Diagnostics, Roche Diagnostics, Sebia and Tosoh), we obtained a global variability of 5.3% (in terms of CV) and of 3.8% at an HbA1c value of 37.4 mmol/mol (sample 1) and 62.0 mmol/mol (sample 2), respectively. With a goal for the allowable total error (TE) of 6.0%, 70% and 77% of the participants met this criterion for samples 1 and 2, respectively. Inter-laboratory CVs,were between 3.3 and 5.0% and between 2.2 and 3.7% for samples 1 and 2, respectively. Tosoh users registered the smallest inter-laboratory CV in sample 1, and Sebia's in sample 2. With regard to trueness, all methods had a mean bias of =2.8% with respect to the target values, with the exception of Tosoh (bias of +6.1 and +5.8%, for samples 1 and 2, respectively). Conclusion: These results are in good agreement with those obtained by the CAP 2014 GH2-A survey, suggesting then that still there is an urgent need for improving a significant part of themethods currently used to measure HbA1c. © 2015 Elsevier B.V. Source


Drion I.,Diabetes Center | Cobbaert C.,Leiden University | Groenier K.H.,Diabetes Center | Groenier K.H.,University of Groningen | And 7 more authors.
BMC Nephrology | Year: 2012

Background: Non-equivalence in serum creatinine (SCr) measurements across Dutch laboratories and the consequences hereof on chronic kidney disease (CKD) staging were examined. Methods. National data from the Dutch annual external quality organization of 2009 were used. 144 participating laboratories examined 11 pairs of commutable, value-assigned SCr specimens in the range 52-262 mol/L, using Jaffe or enzymatic techniques. Regression equations were created for each participating laboratory (by regressing values as measured by participating laboratories on the target values of the samples sent by the external quality organization); area under the curves were examined and used to rank laboratories. The 10th and 90th percentile regression equation were selected for each technique separately. To evaluate the impact of the variability in SCr measurements and its eventual clinical consequences in a real patient population, we used a cohort of 82424 patients aged 19-106 years. The SCr measurements of these 82424 patients were introduced in the 10 th and 90th percentile regression equations. The newly calculated SCr values were used to calculate an estimated glomerular filtration rate (eGFR) using the 4-variable Isotope Dilution Mass Spectrometry traceable Modification of Diet in Renal Disease formula. Differences in CKD staging were examined, comparing the stratification outcomes for Jaffe and enzymatic SCr techniques. Results: Jaffe techniques overestimated SCr: 21%, 12%, 10% for SCr target values 52, 73 and 94 mol/L, respectively. For enzymatic assay these values were 0%, -1%, -2%, respectively. eGFR using the MDRD formula and SCr measured by Jaffe techniques, staged patients in a lower CKD category. Downgrading to a lower CKD stage occurred in 1-42%, 2-37% and 12-78.9% of patients for the 10th and 90th percentile laboratories respectively in CKD categories 45-60, 60-90 and >90 ml/min/1.73 m 2. Using enzymatic techniques, downgrading occurred only in 2-4% of patients. Conclusions: Enzymatic techniques lead to less variability in SCr measurements than Jaffe techniques, and therefore result in more accurate staging of CKD. Therefore the specific enzymatic techniques are preferably used in clinical practice in order to generate more reliable GFR estimates. © 2012 Drion et al.; licensee BioMed Central Ltd. Source


Rohlfing C.,University of Missouri | Hanson S.,University of Missouri | Weykamp C.,European Reference Laboratory | Siebelder C.,European Reference Laboratory | And 5 more authors.
Clinica Chimica Acta | Year: 2016

Background: Hemoglobin C, D Punjab, E or S trait can interfere with hemoglobin A1c (HbA1c) results. We assessed whether they affect results obtained with 12 current assay methods. Methods: Hemoglobin AA (HbAA), HbAC, HbAD Punjab, HbAE and HbAS samples were analyzed on one enzymatic, nine ion-exchange HPLC and two Capillary Electrophoresis methods. Trinity ultra2 boronate affinity HPLC was the comparative method. An overall test of coincidence of least-squared linear regression lines was performed to determine if HbA1c results were statistically significantly different from those of HbAA samples. Clinically significant interference was defined as >7% difference from HbAA at 6 or 9% HbA1c compared to ultra2 using Deming regression. Results: All methods showed statistically significant effects for one or more variants. Clinically significant effects were observed for the Tosoh G8 variant mode and GX (all variants), GX V1.22 (all but HbAE) and G11 variant mode (HbAC). All other methods (Abbott Architect c Enzymatic, Bio-Rad D-100, Variant II NU and Variant II Turbo 2.0, Menarini HA-8180T thalassemia mode and HA-8180V variant mode, Sebia Capillarys 2 and Capillarys 3) showed no clinically significant differences. Conclusions: Several methods showed clinically significant interference with HbA1c results from one or more variants which could adversely affect patient care. © 2016 Elsevier B.V. Source


John W.G.,Norwich University | Little R.,University of Missouri | Sacks D.B.,U.S. National Institutes of Health | Weykamp C.,European Reference Laboratory | And 6 more authors.
Clinical Chemistry and Laboratory Medicine | Year: 2015

Background: The accurate and precise quantification of HbA1c is essential for the diagnosis and routine monitoring of patients with diabetes. We report an evaluation of the Trinity Biotech Premier Hb9210 analyser (Bray, Ireland/Kansas City, MO, USA), a boronate affinity chromatography-based high performance liquid chromatography (HPLC) system for the measurement of glycated haemoglobin. Methods: We evaluated the analytical performance of the Hb9210 as part of a multicentre evaluation. The effect of haemoglobin variants, other potential interferences and the performance in comparison to both the International Federation of Clinical Chemistry and Laboratory Medicine (IFCC) and National Glycohemoglobin Standardization Program (NGSP) reference systems, was assessed. Most of the centres participating also act as reference laboratories for both the IFCC standardisation network for HbA1c and the NGSP. Results: The combined data from all centres showed total coefficients of variation (CV) of 2.71%, 2.32% and 2.14% at low, medium and high values, respectively, for mmol/mol (SI units) and 1.62%, 1.59% and 1.68% for % (NGSP units), which are well below the recommended upper limits of 3% CV for mmol/mol (SI units) and 2% CV for % (NGSP). The analyser showed a good correlation to HbA1c methods currently used in clinical practice and the IFCC reference method procedure. Haemoglobin variants AC, AS, AE and AD do not affect the measurement of HbA1c. Overall the Hb9210 performs well across the whole analytical range. Conclusions: The Hb9210 performs well and is suitable for clinical application in the analysis of HbA1c. © 2015 by De Gruyter 2015. Source


Weykamp C.,Queen Beatrix Hospital | Weykamp C.,European Reference Laboratory | John G.,Norwich University | Gillery P.,University Hospital of Reims | And 8 more authors.
Clinical Chemistry | Year: 2015

BACKGROUND: A major objective of the IFCC Task Force on Implementation of HbA1c Standardization is to develop a model to define quality targets for glycated hemoglobin (Hb A1c). METHODS: Two generic models, biological variation and sigma-metrics, are investigated. We selected variables in the models for Hb A1c and used data of external quality assurance/proficiency testing programs to evaluate the suitability of the models to set and evaluate quality targets within and between laboratories. RESULTS: In the biological variation model, 48% of individual laboratories and none of the 26 instrument groups met the minimum performance criterion. In the sigmametrics model, with a total allowable error (TAE) set at 5 mmol/mol (0.46% NGSP), 77% of the individual laboratories and 12 of 26 instrument groups met the 2σ criterion. CONCLUSIONS: The biological variation and sigma-metrics models were demonstrated to be suitable for setting and evaluating quality targets within and between laboratories. The sigma-metrics model is more flexible, as both the TAE and the risk of failure can be adjusted to the situation - for example, requirements related to diagnosis/monitoring or international authorities. With the aim of reaching (inter)national consensus on advice regarding quality targets for Hb A1c, the Task Force suggests the sigma-metrics model as the model of choice, with default values of 5 mmol/mol (0.46%) for TAE and risk levels of 2σ and 4σ for routine laboratories and laboratories performing clinical trials, respectively. These goals should serve as a starting point for discussion with international stakeholders in the field of diabetes. © 2015 American Association for Clinical Chemistry. Source

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