Quality specifications for evaluation and comparison of performance among external quality assessment schemes in occupational and environmental laboratory medicine

Abstract

Quality specifications (QS) are proposed for lead in blood and for aluminium, copper, selenium and zinc in serum as part of
the aim to set standards of performance for laboratories so that results can be demonstrated to be fit for the purpose to
which they are applied. The QS were established taking account of the analytical state-of-the-art, physiological variations
in the concentrations of the analyte and the clinical purpose for which the assay is to be used. A procedure was devised that
uses these QS to give equivalence of assessment among external quality assessment schemes (EQAS), thus avoiding conflicting
information which has been demonstrated in the past. Advantages of this procedure are: to provide direct comparison of performance
of laboratories taking part in different schemes, to provide equivalence of assessment of laboratory performance necessary
to establish mutual recognition agreements, and to demonstrate the fitness for purpose of results from participants.