Effects of analytical goals on evaluating performance of hba1c measuring method

Abstract

HbA1c measuring plays a critical role in the monitoring and diagnosis of diabetes. So, analytical performance of its measuring method must be acceptable. It is the responsibility of clinical laboratories to continuously monitor the performance of commercial methods in use, both by the implementation of a proper internal quality control (IQC) and participation in appropriately organized external quality assessment schemes (EQAS). Efficieny of both of IQC and EQA is strongly affected by selected analytical goals. During eighteenth and nineteenth runs of external quality assessment program (EQAP), in Jully 2014 and November 2014, two freshly prepared commutable patient QC samples were sended to 650 and 858 laboratories which used five common HbA1c kits. Target values for total group and also for peer groups were calculated. Performance of each laboratory was determined according to two different allowable total errors (TEa), including ±6% and ±20%, which are suggested by National Glycohemoglobin Standardization Program (NGSP) and Reference Health Laboratory of Iran, respectively. when we used TEa of ±20% for evaluating HbA1c method performance, about 11% and 9% of participant laboratories had unacceptable performance during EQAP-18 and EQAP-19. respectively. But when this evalution was performed according to TEa of ±6%, unacceptable results increased significantly to 50%and 55%, respectively. Using improper analytical goals leads to misinterpretation of IQC and EQA results. Analytical goals must be defined in a such way that the test could save its clinical usefulness. In order to maintain clinical usfulness of HbA1c results we need to reduce TEa of ±20% to ±6% and improve HbA1c measuring method performance.