Six Years' Experience of Accuracy-Based Proficiency Testing for HbA1c in Korea

ABSTRACT

BACKGROUND: The proficiency testing (PT) program for HbA1c, performed by the Korean Association of External Quality Assessment Service (KAEQAS), first started in 2007. From 2007 to 2008, the results were assessed using means as the standard within a peer group (identical method group). However, the assessment method changed to accuracy-based PT in 2009. This study aimed to analyse the results of an external quality assessment of HbA1c from 2009 to 2014. METHODS: Based on the data obtained from the external quality assessment of HbA1c from 2009 to 2014, we analysed the number of participating institutions, response rate, 'unacceptable' result rate, bias from the target value, and CVs according to each instrument code. RESULTS: The number of participating institutions was only 180 in 2009. However, it increased over the next 5 years, and as of 2014, 345 institutions were enrolled. The response rates were 93.8% to 99.1%. Since 2009, the measurement method changed and most of the participating institutions now use the high-performance liquid chromatography (HPLC) method. As of 2014, the HPLC method showed small bias from the target value and inter-laboratory CVs (<3.5%), demonstrating satisfactory performance. Immunoassays and point-of-care testing (POCT) demonstrated relatively unsatisfactory performance, showing larger inter-laboratory CVs compared to those obtained with the HPLC method, with some of them exceeding the acceptance limit of +/-8% of the target value. CONCLUSIONS: As of 2014, relatively large-scale laboratories are participating in the accuracy-based PT for HbA1c. According to the accuracy-based PT for HbA1c, POCT showed the highest 'unacceptable' rate and imprecision. Therefore, small-scale laboratories mostly using POCT for HbA1c measurement should be encouraged to participate in the accuracy-based PT program for HbA1c, and the external quality assessment program undertaken by KAEQAS should be expanded.