Verifica della riferibilità metrologica dei dispositivi medico-diagnostici in vitro : responsabilità e strategie

Verification of in vitro medical diagnostics (IVD) metrological traceability: strategies and responsibilities. To be accurate and equivalent laboratory results should be traceable to higher-order references. Furthermore, their analytic quality should fulfil acceptable measurement uncertainty as defined to fit the intended clinical use. To this aim, IVD manufacturers should define a calibration hierarchy to assign traceable values to their system calibrators and to fulfil during this process uncertainty limits for calibrators that should represent a proportion of the uncertainty budget allowed for clinical laboratory results. It is important that end-users may know and verify how manufacturers have implemented the traceability of their calibrators and estimated the corresponding uncertainty. Currently, the full information about traceability and uncertainty of calibrator is not available as manufacturers only provide the name of higher-order reference material and/or procedure to which the assay calibration is traceable without any description of steps and their corresponding uncertainty of the implemented traceability chain. Important post-market tools for IVD traceability surveillance are related to the verification by clinical laboratories of the consistency of declared performance during daily operations performed in accordance with the manufacturer’s instructions and the organization of appropriately structured EQAS. The former activity should be accomplished by analyzing system control materials and confirming that current measurements are in the manufacturer’s established control range. With regard to EQAS, it is mandatory that target values to materials are assigned with reference procedures by an accredited reference laboratory, that materials are commutable and a clinically allowable inaccuracy for participant’s results is defined in order to prove the suitability of laboratory measurements in clinical setting.