Report on a common survey in clinical laboratories in Belgium and in The Netherlands: immunoassays

A common survey for immunoassays was organized for Belgian and Dutch laboratories. We compared the different statistical approaches used in the two schemes; both approaches lead to comparable results. Differences in overall consensus values and overall precision are related to a different selection of kits in the two countries. When analyzing results from users of representative kits in both countries, we found a very good correlation in accuracy but detected also some significant differences in precision for some samples for cortisol and theophylline determinations. For some observed differences there is actually no acceptable explanation.