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This Article Full Text Full Text (PDF) Supplemental Data All Versions of this Article: clinchem.2009.129726v1 55/10/1876    most recent Alert me when this article is cited Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Google Scholar Articles by Shiesh, S.-C. PubMed PubMed Citation Articles by Shiesh, S.-C.

Proficiency Testing of Hb A_1c: A 4-Year Experience in Taiwan and the Asian Pacific Region

¹ Department of Medical Laboratory Science and Biotechnology, National Cheng Kung University, Tainan, Taiwan;² National Glycohemoglobin Standardization Program,University of Missouri, Columbia, Missouri; ³ Institute of Medical Technology, National Taiwan University, Taipei, Taiwan; ⁴ Department of Core Clinical Pathology and Biochemistry, Royal Perth Hospital, Perth, Australia; ⁵ Department of Biomedical Sciences, MAHSA University College, Damansara Heights, Kuala Lumpur, Malaysia;

^aaddress correspondence to this author at: 1 University Road, Department of Medical Laboratory Science and Biotechnology, National Cheng Kung University, Tainan, Taiwan 70101. Fax +886-6-2363956; e-mail hsieh{at}mail.ncku.edu.tw

Abstract

Background: The correlation between hemoglobin A_1c (Hb A_1c) and risk for complications in diabetic patients heightens the need to measure Hb A_1c with accuracy. We evaluated the current performance for measuring Hb A_1c in the Asian and Pacific region by examining data submitted by laboratories participating in the Taiwan proficiency-testing program.

Methods: Five fresh-pooled blood samples were sent to participating laboratories twice each year. The results were evaluated against target values assigned by the National Glycohemoglobin Standardization Program network laboratories; a passing criterion of ±7% of the target value was used. Measurement uncertainty at Hb A_1c concentrations of 7.0% and 8.0% were determined.

Results: A total of 276 laboratories from 11 countries took part in the Hb A_1c survey. At the Hb A_1c concentrations tested method-specific interlaboratory imprecision (CVs) were 1.1%–13.9% in 2005, 1.3%–10.1% in 2006, 1.2%–8.2% in 2007, and 1.1%–6.1% in 2008. Differences between target values and median values from the commonly used methods ranged from –0.24% to 0.22% Hb A_1c in 2008. In 2005 83% of laboratories passed the survey, and in 2008 93% passed. At 7.0% Hb A_1c, measurement uncertainty was on average 0.49% Hb A_1c.

Conclusions: The use of accuracy-based proficiency testing with stringent quality criteria has improved the performance of Hb A_1c testing in the Asian and Pacific laboratories during the 4 years of assessment.