Quality specifications for reference methods

Reference methods are a key element to the objective of traceability in lab oratory medicine. However, to serve this purpose adequately, minimum analyt ical quality specifications are required. Here, possible strategies for der iving such specifications are presented, being based on concepts developed before by a European Working Group. Distinction is made between "genuine re quirements" for reference methods (direct calibration with primary referenc e materials: absence of sample-related effects) and "performance specificat ions" (limits for random, systematic and total error, the latter in associa tion with the number of measurements). While the former requirements are co nsidered as conditio sine-qua-non, the latter specifications should be vari able, which means that they should be tailored to the specific application of the methods. In general, it is advocated to derive performance specifica tions for reference methods from desirable specifications of routine method s (analyte-related), although other models should not be ruled out beforeha nd. Further, it is recommended that reference laboratories make special eff orts to demonstrate and maintain a uniform level of quality of reference me thods.