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A new integrated tool for assessing and monitoring test comparability and stability

Performing accurate measurements, comparable over time and location and across assays, is essential to ensure appropriate clinical practice [1] . One step towards achieving this goal is using assays that are metrologically traceable to a higher order reference measurement system or harmonized using internationally recognized procedures [2, 3] . In Europe, diagnostic manufacturers are required by the European Union Directive on in vitro diagnostic medical devices to demonstrate the metrological traceability of their analytical systems [4] . Thus, in principle, laboratories using CE-marked homogeneous systems (calibrator, reagent and instrument from the same manufacturer) can assume accuracy and interchangeability of their measurements results. However, it is the task of clinical laboratory profession to verify that the alignment process has been correctly implemented and that the performances of marketed systems are really appropriate for their clinical use. In particular, the laboratory has to verify the consistency of the manufacturer ’ s declared performance during routine operations performed strictly in accordance with their instruction, and to participate in external quality assessment (EQA)/proficiency testing (PT) schemes structured so that they provide objective information on the analytical quality of measurements performed by clinical laboratories and on the performances of the peer group assays [5 – 7] . EQA programs using commutable materials and reference method target values are becoming more widespread, but until now they are applied only to few constituents (i.e., hemoglobin A 1c ) [8, 9] . Generally, an EQA program for clinical biochemistry on serum, performed by an independent national or regional center, with a sufficient number of participants so that the peer groups can be well defined, consists in a panel of about 25 – 35 measurands. Even if controls materials are made ad hoc, namely to evaluate clinically important concentrations, the commutability for all measurands and diagnostic systems is difficult to be achieved. Moreover, being target values by reference methods available for a few measurands and extremely expensive, it is very difficult to get a reference target values for all measurands. Finally, just for the intrinsic design of an EQA program, the data are not available in real time. In this issue of Clinical Chemistry and Laboratory Medicine , the team of Thienpont and colleagues, whose remarkable dedication to the improvement of quality, standardization and harmonization of clinical laboratory testing is well appreciated at an international level and by the readers of the journal [10 – 14] , describes a new project aimed to establish a bottom-up cooperation between laboratories and manufacturers, so that they can pursue the common objective of assessing test comparability and stability of laboratory results [15] . The “ Empower ” project, proposed as an independently operated “ online ” tool that should monitor comparability and long-term stability between peer groups and laboratories, comprises four pillars: 1) Master comparison with panels of frozen single-donation samples; 2) Monitoring of patients percentiles; 3) Monitoring of IQC data, both across laboratories and manufacturers; 4) Conceptual and statistical education about analytical quality in the medical laboratory and elaboration of actionable experiments for analytical quality management and assurance. Laboratories are free to participate in all pillars of the project or to select the most appropriate one(s) for their purpose and the paper reports the status of the project with respect to the first two points. The focus of the master comparisons, which are conducted across assays and laboratories, is on how well the intrinsic analytical quality of assays released by the respective manufacturers is reproduced by the end users under “ field ” conditions all over the world. Results about master comparison with a panel of 20 frozen single donation samples for calcium, magnesium, albumin, total protein [16, 17] , sodium [18] , creatinine, glucose, phosphate, uric acid, total cholesterol, HDL cholesterol, LDL cholesterol and triglycerides [19] , have been previously described. In a recent survey AST, ALT, LDH, GGT and ALP, sodium, potassium and chloride have been added. A limitation of these studies was that for the most measurands the target values were the “ all method trimmed mean ”