Why Metrological Traceability Matters in Medical Laboratory Diagnostics.

Application of the results provided by medical laboratories plays an essential role in medical decision-making. This is not limited to diagnosis and monitoring of disease but also involves its use in other phases of the health continuum, e.g., predisposition, risk stratification, screening, staging, prognosis, and surveillance. With the growing importance of precision medicine, the importance of requirements related to clinical performance, and consequently analytical performance of laboratory tests, also grows. To allow the community of laboratory medicine to translate clinical need into a test arsenal with adequate performance, the application of metrology concepts is essential. This paper summarizes, for all steps in the examination process from test development to clinical interpretation, why and how metrological traceability is a fundamental requirement for adequate medical decision-making and is critical for correct use of test results in algorithms and artificial intelligence-led approaches. This includes the importance of metrology concepts and their correct implementation for obtaining equivalence of test results upon cross-facility result exchange for primary or secondary use in healthcare and research. This is not limited to biochemistry and hematology but is also of importance to other areas of laboratory medicine, including microbiology. This paper provides an overview of the purposes of the underappreciated science of metrology in modern laboratory medicine and its importance to patients and caregivers.