Vademecum EBLM in the clinical pathology laboratory

Abstract

Laboratory medicine plays a central role in clinical decision-making, yet the interpretation of analytical and diagnostic performance parameters is often inconsistent in both scientific literature and routine practice. Evidence-Based Laboratory Medicine (EBLM) provides a structured framework for evaluating the quality, clinical utility, and appropriate use of in vitro diagnostic tests. This vademecum offers a practical and integrated overview of the main concepts required to assess analytical and diagnostic performance in the clinical pathology laboratory. Particular attention is given to analytical sensitivity, selectivity, limits of detection and quantification, measurement range, robustness, accuracy, trueness, precision, measurement uncertainty, reference intervals, and Reference Change Value. The document also examines the diagnostic implications of cut-off selection, sensitivity, specificity, diagnostic accuracy, ROC curves, area under the curve, Youden Index, likelihood ratios, predictive values, pre-test and post-test probability, and the influence of disease prevalence. By clarifying the distinction between prevalence-independent and prevalence-dependent parameters, the article highlights the importance of integrating laboratory data with clinical context and Bayesian reasoning. Sequential and parallel testing strategies are also discussed as tools to improve diagnostic predictive value. Finally, a case study illustrates the selection of optimal cut-off values in quantitative tests through ROC and diagnostic performance curves. This vademecum aims to support laboratory professionals in critically appraising diagnostic evidence, improving test interpretation, and contributing more effectively to patient-centred clinical decision-making.