Background: The aim of this study was to provide inter-laboratory imprecision comparisons of different groups of diagnostic systems as well as a comparison of professional laboratories with medical offices performance on the basis of 88,429 glucose results obtained in external quality assessment (EQA) schemes organized by three European EQA centers between 1996 and 2007.
Methods: A simple, non-parametrical statistical model suited to all EQA results, including outliers, was used to calculate yearly and global performance.
Results: The best performance was obtained from professional laboratories with a group of three diagnostic systems--Hitachi, Integra, and Vitros, followed by Cobas Mira, and finally by Reflotron. For medical offices, the best performance was achieved with the Cobas Mira diagnostic systems, followed by the Reflotron, SpotChem, and Vitros DT60 diagnostic systems. A slight but overall improvement in performance over time was observed for most diagnostic devices.
Conclusions: The analysis of glucose EQA results collected over a 12-year period showed that professional laboratories obtained better performances than medical offices, and that a general improvement in yearly performance was observed for both types of laboratories.