Abstract
After Hemoglobin A1c (HbA1c), therapeutic targets for monitoring diabetes therapy were recommended, first, National Glycohemoglobin Standardization Program (NGSP), then, the International Federation of Clinical Chemistry and Laboratory Medicine (IFCC) developed standardization initiatives. The aim of this article is to demonstrate the role of a proficiency testing (PT) programs in monitoring the long-term effect of these initiatives and the current status of HbA1c measurement. Measurement precision as a coefficient of variation (CV), measurement bias (bias), and satisfactory HbA1c result rates in proficiency testing (PT) surveys were evaluated using fresh single donor whole blood PT items and assigned values from a NGSP-certified secondary reference laboratory. Between 2000 and 2010, both CV and bias of the IC measurement method showed a decreasing trend. While the CV of the HPLC measurement method decreased, no significant change was observed in its bias. The rates of satisfactory HbA1c results in PT surveys were higher in HPLC users than IC users. In 2010, the average CVs in HPLC and IC groups were 2.6 and 3.4 %, biases were 2.7 and 1.8 %, and corresponding total error (TE) estimates were 7.8 and 8.5 %, respectively. These TE values were higher than the maximum permissible measurement error of 7 %, developed based on clinical use of the test. The NGSP and the IFCC networks have promoted improvements in HbA1c testing; however, tightening of NGSP method certification criteria seems to be necessary to achieve a maximum permissible measurement error of 7 %.
References
Little RR, Rohlfing CL, Sacks DB, National Glycohemoglobin Standardization Program (NGSP) Steering Committee (2011) Status of hemoglobin A1c measurement and goals for improvement: from chaos to order for improving diabetes care. Clin Chem 57:205–214
Steffes M, Cleary P, Goldstein D, Little R, Wiedmeyer HM, Rohlfing C, England J, Bucksa J, Nowicki M (2005) Hemoglobin A1c measurements over nearly two decades: sustaining comparable values throughout the Diabetes Control and Complications Trial and the Epidemiology of Diabetes Interventions and Complications study. Clin Chem 51:753–758
Kaiser P, Akerboom T, Ohlendorf R, Reinauer H (2010) Liquid chromatography-isotope dilution-mass spectrometry as a new basis for the reference measurement procedure for hemoglobin A1c determination. Clin Chem 56:750–754
Sacks DB for the ADA/EASD/IDF working group of the HbA1c Assay (2005) Global harmonization of hemoglobin A1c. Clin Chem 51:681–683
Hoelzel W, Weykamp C, Jeppsson JO, Miedema K, Barr JR, Goodall I, Hoshino T, John WG, Kobold U, Little R, Mosca A, Mauri P, Paroni R, Susanto F, Takei I, Thienpont L, Umemoto M, Wiedmeyer HM, IFCC Working Group on HbA1c Standardization (2004) IFCC reference system for measurement of hemoglobin A1c in human blood and the national standardization schemes in the United States, Japan, and Sweden: a method-comparison study. Clin Chem 50:166–174
Geistanger A, Arends S, Berding C, Hoshino T, Jeppsson JO, Little R, Siebelder C, Weykamp C, IFCC Working Group on Standardization of Hemoglobin A1c (2008) Statistical methods for monitoring the relationship between the IFCC reference measurement procedure for hemoglobin A1c and the designated comparison methods in the United States, Japan, and Sweden. Clin Chem 54:1379–1385
Hanas R, John G, International HbA Consensus Committee (2010) 2010 consensus statement on the worldwide standardization of the hemoglobin A1c measurement. Pediatric Diabetes 11:209–211
Little RR, Rohlfing CL, Wiedmeyer HM, Myers GL, Sacks DB, Goldstein DE, NGSP Steering Committee (2001) The national glycohemoglobin standardization program: a five-year progress report. Clin Chem 47:1985–1992
Weykamp C, John WG, Mosca A, Hoshino T, Little R, Jeppsson JO, Goodall I, Miedema K, Myers G, Reinauer H, Sacks DB, Slingerland R, Siebelder C (2008) The IFCC reference measurement system for HbA1c: a 6-year progress report. Clin Chem 54:240–248
Sacks DB, Arnold M, Bakris GL, Bruns DE, Horvart AR, Kirkman MS, Lernmark A, Metzger BE, Nathan DM (2011) Guidelines and recommendations for laboratory analysis in the diagnosis and management of diabetes mellitus. Clin Chem 57(6):e1–e147
ISO 13528:2005(E), Statistical methods for use in proficiency testing by interlaboratory comparisons (2005) International Organization for Standardization, Geneva
Westgard JO (2002) Basic QC practices. Westgard QC Inc, Madison, WI
NGSP Certified Methods (2011) http://www.ngsp.org/docs/methods.pdf. Accessed June 2011
American Diabetes Association Standards of medical care in diabetes 2011 (2011) Diabetes Care 34(Suppl 1):S11–S61
American Diabetes Association Standards of medical care in diabetes 2010 (2010) Diabetes Care 33(Suppl 1):S11–S61
Fraser CG (2001) Biological variation: from principles to practice. AACC Press, Washington, DC
Biological Variation Database Specifications 2010 update of Ricos C, Alvarez V, Cava F, Garcia-Lario JV, Hernandez A, Jimenez CV, Minchinela J, Perich C, Simon M. (1999) “Current databases on biologic variation: pros, cons and progress.” Scand J Clin Lab Invest 59:491–500. http://www.westgard.com/biodatabase1.htm. Accessed August 2011
Kilpatrick ES, Maylor PW, Keevil BG (1998) Biological variation of glycated hemoglobin. Implications for diabetes screening and monitoring. Diabetes Care 21:261–264
Garde AH, Hansen AM, Skovgaard LT, Christensen JM (2000) Seasonal and biological variation of blood concentrations of total cholesterol, dehydroepiandrosterone sulfate, hemoglobin A(1c), IgA, prolactin, and free testosterone in healthy women. Clin Chem 46:551–559
Rohlfing C, Wiedmeyer HM, Little R, Grotz VL, Tennill A, England J, Madsen R, Goldstein D (2002) Biological variation of glycohemoglobin. Clin Chem 48:1116–1118
Phillipou G, Phillips PJ (1993) Intraindividual variation of glycohemoglobin: implications for interpretation and analytical goals. Clin Chem 39:2305–2308
Friedecký B, Kratochvíla J, Budina M, Šperligová I (2010) The results of HbA1c measurement and its comparison with reference method values in an EQA programme. Accred Qual Assur 15:239–243
Sofronescu AG, Williams LM, Andrews DM, Zhu Y (2011) Unexpected hemoglobin A1c results. Clin Chem 57:153–157
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Aslan, B., Gun-Munro, J. & Flynn, G.J. Role of proficiency testing in monitoring of standardization of hemoglobin A1c methods. Accred Qual Assur 17, 419–424 (2012). https://doi.org/10.1007/s00769-012-0907-1
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DOI: https://doi.org/10.1007/s00769-012-0907-1