The results of HbA1c measurement and its comparison with reference method values in an EQA programme

• Published in: Accreditation and quality assurance Vol. 15; no. 4; pp. 239 - 243
• Main Authors: Friedecký, Bedřich, Kratochvíla, Josef, Budina, Marek, Šperlingová, Ilona
• Format: Journal Article Conference Proceeding
• Language: English
• Published: Berlin/Heidelberg Springer-Verlag 01.04.2010; Springer; Springer Nature B.V
• Subjects: Analytical Chemistry; Bias; Biochemistry; Chemistry; Chemistry and Materials Science; Chromatographic methods and physical methods associated with chromatography; Chromatography; Coefficient of variation; Commercial Law; Ecotoxicology; Exact sciences and technology; Food Science; Glucose; Hemoglobin; Immunoassay; Indicators; Laboratories; Marketing; Mathematical analysis; Measurement methods; Methods; Miscellaneous; Other chromatographic methods; Practitioner's Report; Quality assessment; Reference materials; Reproducibility; Systematic errors; Uncertainty; Uncertainty; IFCC method; HbA; External quality assessment; Immunochemistry; measurement; HPLC; Analytical indicator; Bias; Estimation; Use; HPLC chromatography; Time; Laboratory; Implementation; Immunological method; Chemistry; Target; Survey; Reproducibility; Quality; Measurement method; Comparative study; Variation coefficient
• ISSN: 0949-1775; 1432-0517
• DOI: 10.1007/s00769-009-0626-4

This article describes the effect of a change in reference method for HbA 1c measurement on results in our EQA programme. Important indicators of analytical quality, particularly reproducibility, bias and uncertainty, were assessed. Basic analytical quality indicators for the measurement of HbA 1c in an EQA survey during 2000–2008 were evaluated. Three EQA surveys per year were performed. Usually there were more than 200 participating laboratories in each survey. Reproducibility, systematic differences, bias, and methodology changes before and after IFCC reference method implementation were determined. In the EQA surveys, target values traceable to the IFCC reference method are used. Estimation of the combined uncertainty of the result was a voluntary part of the surveys and was reported by 50% of participating laboratories. Reproducibility of all participants’ measurements was close to the target value of CV = 5.0% (coefficient of variation). The group of participants using HPLC methodology had reproducibility lower than 5.0% in each survey, whilst the immunochemistry group usually had CV values more than 6.0%. The differences in individual results from target values ranged in the interval ±12% for HPLC methods but more (−8 to +30%) for immunochemistry methods. During the monitored time interval the number of participants using HPLC methods increased up to 70% whilst the number of participants using immunochemistry methods decreased approximately to 30%. The combined uncertainty ( u c ) reported by participants varies between 4.0 and 4.5% for HbA 1c values between 30 and 90 mmol/mol. No significant differences between precision and systematic errors (bias) after the implementation of IFCC method of measurement for HbA 1c to routine processes for HPLC were observed. Immunochemical methods do not fulfil requirements for analytical reproducibility.