In 2023 the ECAT has introduced an advanced methodology for the evaluation of Z-scores obtained in external quality assessment surveys, the so-called bivariate z-score analysis (1). In a practical case study, the value of this bivariate z-score analysis has been demonstrated.
Abstract
It is important that a clinical laboratory has implemented appropriate procedures for quality control, which includes both internal quality control (IQC) and external quality assessment (EQA) with the common goal to detect systematic errors and random errors. It is the case for both the HemohubR Bayesian tools for IQC results interpretation and the ECAT EQA optimised bivariate z-scores analysis. On a concrete case study, we demonstrate both the higher sensitivity and specificity of optimised bivariate z-scores analysis than the univariate approach. The Bayesian IQC results interpretation like the ECAT analysis confirmed the explicit conclusion i.e. an increase of the random error corresponding to the increase of the inter assay coefficient of variation (CV) at the date of EQA samples runs. Improvement of repaired dysfunction could be then daily observed on IQC results and then confirmed on EQA results thanks to the complementarity of the two approaches.
Ann Biol Clin (Paris) 2024 Vol. 82 Issue 6 Pages 1-6
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(1) Meijer, P., F. Sobas and P. Tsiamyrtzis, Assessment of accuracy of laboratory testing results, relative to peer group consensus values in external quality control, by bivariate z-score analysis: the example of D-Dimer. Clin Chem Lab Med, 2024; 62: 1548-1556.