Retrospective analysis of 55,769 HbA1c EQA results obtained from professional laboratories and medical offices participating in surveys organized by two European EQA centers over a nine-year period

Abstract

External Quality Assessment (EQA) is an essential tool for laboratories to monitor the performances of their analyses. It also allows a comparison of methods and types of laboratories (professional laboratories vs. medical offices). We, therefore, compared 55,769 HbA1c EQA results obtained between 1999 and 2008 by laboratories participating in EQA schemes organized by two European centers, Switzerland (center 1) and France (center 2). We used simple, nonparametrical statistics suited to EQA results to calculate the yearly and global precision performances. All the results, including the outliers, were included in the calculations. The best global precision performances were obtained by professional laboratories and medical offices using DCA POCT devices, followed by professional laboratories with the Integra, Hitachi, Cobas Mira, and HPLC groups of devices, and finally by both types of laboratories with the NycoCard POCT devices. When considering yearly precision performances, an overall improvement over time was observed for almost all diagnostic devices of center 1, whereas the trend was less clear for center 2. The HbA1c EQA results collected and analyzed over a 9-year period showed that the DCA POCT devices used either by professional laboratories or medical offices had better reproducibility than laboratory devices (other than POCT) and that a general improvement of yearly precision performances was observed, especially when frequent EQA schemes were organized.