What is EQA?
Medical laboratory quality management is developing rapidly and keeps evolving every day. However, analytical quality is still the primary issue since none of the other laboratory quality attributes are relevant if analytical quality is not achieved. Quality control (QC) was first introduced to the medical sphere long ago. It means statistical quality control used in laboratories to monitor the routine execution of testing processes. It helps to identify errors that may occur during the working process and correct problems before the launch of the product or sphere. Specifically, internal quality control (IQC) and external quality assessment (EQA) programs are used to assess and continually improve analytical quality.
Additional Testing Possibilities
Currently, the terms “external quality assessment” (EQA) and “proficiency testing” (PT) are used interchangeably as valuable tools in the quality improvement process for clinical laboratory services. However, the primary goals of EQA are educational and can be supported by additional elements, such as specific schemes aimed at extending assessment to all phases of the testing cycle, including interpretation of results. According to a generally accepted definition, a TC is “a program in which multiple samples are periodically sent to members of a group of participating laboratories for analysis and/or identification, in which the results of each laboratory are compared with the results of other laboratories in the group and/or with an assigned value, and reported to the participating laboratories and others”.
Additional Information
On the other hand, a better definition of EQA is “integrated medical laboratory quality assurance professional activities”, which emphasizes its use for self-assessment and continuous quality improvement in medical laboratories.
Currently, QA providers around the world provide a report for each proposed assay that aims to inform each participating laboratory about the analytical performance, the effectiveness of the diagnostic methods/systems used, and the comparability of results by analyzing the statistics of the different diagnostics/systems (Kristensen & Meijer, 2017). In addition, some authors advocate that the quality assessment report evaluates analytical performance not only in terms of overall error (OE) but also in terms of bias and inaccuracy to better examine the causes of error.
The Accuracy of Provided Results
To ensure that accurate information is provided, QA providers should develop systems in accordance with approved guidelines and recommendations as well as international standards. Awareness of the interchangeability of reference materials should be raised, which is an important feature to avoid any misinterpretation. In particular, interchangeability can affect the data processing procedure and the identification of the assigned value, the choice of analytical specifications (APS) and the evaluation of the degree of metrological traceability of analytical test procedures using QMD.
However, finding interchangeable standard samples for all tests covered by the programs can be challenging for QA providers, increasing workload and costs. The inability to achieve or determine interchangeability for one or more of the measured parameters or for a particular test procedure should be considered when selecting how results are processed.
If the degree of interchangeability differs between different diagnostic systems that use the same amount of devices, but they are all based on the same method, results should be treated as per the whole diagnostic system without separating it into different categories in order to prevent estimates when comparing statistics from different groups. In addition, evaluating laboratory results based on the consensus value associated with the diagnostic system rather than the method ensures that unsatisfactory results are associated with interchangeability problems as they are not erroneously attributed to laboratory procedures.
The Difference Occurring
If a determined value is obtained using an RM (reference material), the difference between the laboratory result and the reference value may be erroneously attributed to a different degree of metrological traceability of the test procedure used rather than to the RM (Jones, 2017). If the reference value is not used, the metrological traceability of the laboratory method/diagnostic system cannot be recognized. For accreditation bodies and regulators they provide objective data on the quality of services provided because EQA/PT scores have been shown to reflect the quality of patient sample testing. This property is commonly referred to as “commutability.”
Accreditation
A commutative sample is one that has an equivalent mathematical relationship between all the different measurement procedures presented in the study, as observed for native clinical samples. Commutativity and its effect on EQA/PT and other reference materials have been described in detail in some reviews (Plebani, 2018). Dividing into “peer groups” that use the same or similar measurement conditions based on combinations of instruments and methods provides useful information for the individual participant but does not improve harmonization and interlaboratory agreement of results.
Summary
Various guidelines and recommendations that have been available in the literature for several years identify relevant quality characteristics (e.g., program characteristics, information to be provided in the participant report, provision of advice and education, independence, and ethical conduct) to ensure the relevance of EQAS. The competence of laboratory professionals, which is key to achieving these goals, should include not only knowledge of the characteristics affecting the reliability of EQAS and APS as defined in the approved documents but also the pragmatism necessary to identify alternatives when the available EQASs prove inadequate.
References
Jones, G. R. D. (2017). The role of EQA in harmonization in laboratory medicine – a global effort. Biochemia Medica, 23–29. Web.
Kristensen, G. B. B., & Meijer, P. (2017). Interpretation of EQA results and EQA-based troubleshooting. Biochemia Medica, 27(1), 49–62. Web.
Plebani, M. (2018). Harmonization in laboratory medicine: more than clinical chemistry? Clinical Chemistry and Laboratory Medicine (CCLM), 56(10), 1579–1586. Web.