Quality specifications in EQA schemes: from theory to practice

Abstract

Background: External quality assessment (EQA) is a tool for quality management in clinical laboratories and its main objectives are assessment of participants and methods performance, training and advice. This paper describes the quality specifications used in EQA schemes of the Centre of Biomedical Research (CRB), in order to design schemes that can assess laboratory reliability performances, meet the changing needs and quality recommendations. Methods: Quality specifications for control materials, statistical procedures and goals to assess laboratory performance have been applied and introduced in EQA schemes managed by CRB. Results: The application of well-defined quality specifications has demonstrated effective. In particular, we report results on alkaline phosphatase and cholesterol obtained using commercial control materials and human serum controls, in two different EQA surveys; the inter-laboratory variability (CVinter%) for troponin I analysed with a diagnostic system and assigned values of CK-MB mass obtained using four different diagnostic systems; the percentage of acceptable performances obtained by means of the application of goals based on clinical criteria, biological variation, state-of-the-art and used for EQA schemes, and referring to some analytes with significant clinical values such as cholesterol, glucose, glycated hemoglobin and sodium. Conclusions: The design of reliable EQA schemes based on evidence-based quality specifications is a pre-requisite for supporting the quality improvement of clinical laboratories.