HbA1c: EQA in Germany, Belgium and the Netherlands using fresh whole blood samples with target values assigned with the IFCC reference system

BACKGROUND: External quality assessment/proficiency test (EQA/PT) organizers play an important role in monitoring the performance of HbA1c measurements. With increasing quality of the assays, HbA1c is increasingly used for diagnosis of diabetes and the demands on EQA/PT organizers themselves are rising constantly. EQA organizers in Germany (INSTAND), Belgium (WIV/IPV), and the Netherlands (SKML) organized a program with commutable samples and target values assigned with the International Federation of Clinical Chemistry and Laboratory Medicine (IFCC) reference system. The aim of this project was to confirm the logistic feasibility of organizing synchronically in the three countries, an accuracy-based EQA program with fresh whole blood, to investigate the performance of HbA1c assays within and across countries and manufacturers, and to review the EQA acceptance limits. METHODS: Throughout 2015, ten fresh whole blood samples were supplied to the participants. Aggregated results were evaluated according to the IFCC model for quality targets at four levels: overall, per country, per manufacturer, and per country per manufacturer. RESULTS: Robust results in summer and winter demonstrated the feasibility of organizing an EQA with fresh whole blood samples in three countries. The overall performances, as well as the performance for each country were very similar: results fell within the IFCC criteria. Although substantial differences between results from different manufacturers were present, the performances of laboratories using tests of the same manufacturer were strikingly similar in the three countries, suggesting that the quality of HbA1c assays is for the most part manufacturer- related. The improved design of the EQA program also suggested that acceptance limits for performance can be reduced to approximately 8%.