Are Your Laboratory Data Reproducible? The Critical Role of Imprecision from Replicate Measurements to Clinical Decision-making

Abstract

Measurement results of biological samples are not perfect and vary because of numerous factors related to the biological samples themselves and the measurement procedures used to analyze them. The imprecision in patients’ laboratory data arising from the mea- surement procedure, known as analytical variation, depends on the conditions under which the data are collected. Additionally, the sample type and sampling time significantly affect patients’ laboratory results, particularly in serial measurements using samples col- lected at different time points. For accurate interpretation of patients’ laboratory data, im- precision—both its analytical and biological components—should be properly evaluated and incorporated into data management. With advancements in measurement technolo- gies, analytical imprecision can be minimized to an insignificant level compared to biologi- cal imprecision, which is inherent to all biomolecules because of the dynamic nature of metabolism. This review addresses: (i) the theoretical background of variation, (ii) the sta- tistical and metrological evaluation of measurement variation, (iii) the assessment of varia- tion under different conditions in medical laboratories, (iv) the impact of measurement variation on clinical decisions, (v) the influence of biases on measurement variation, and (vi) the variability of analytes in human metabolism. Collectively, both analytical and biolog- ical imprecision are inseparable aspects of all measurements in biological samples, with biological imprecision serving as the foundation of personalized laboratory medicine.