Quality assessment of quantitative analytical results in laboratory medicine by root mean square of measurement deviation / Bewertung der Qualität quantitativer analytischer Ergebnisse in der Laboratoriumsmedizin anhand des quadratischen Mittelwertes der Messabweichung

Abstract The current Guidelines of the German Medical Association (“Richtlinien der Bundesärztekammer”, RiLiBÄK) define minimum requirements for the quality assessment of quantitative measurements in laboratory medicine, in particular concerning metrological controls. Results are validated by internal and external quality controls with the help of maximum permissible values for the standard deviation, i.e. imprecision, as well as for systematic deviations of measurement, i.e. bias. In this article, a novel approach is introduced to merge the two parameters “imprecision” and “bias” into a combined characteristic parameter describing the overall deviation of measurement from a target value. It is shown how the established maximum allowable values for imprecision and bias can be converted into a new maximum permissible value for the new validation parameter, hence taking into account the experience with respect to clinical needs as well as the technical constraints to fulfil those requirements. The reduction of two control rules to a single one is a clear simplification of the assessment procedure and, moreover, allows for some flexibility to fulfil the requirements. In addition, a new approach for the validation of individual measurements of control samples is proposed which allows a fast assessment and is better suited to detect critical deviations of measurement as early as possible. Finally, it is shown how the novel approach can be adapted to determine own control rules with the help of control samples of known target values. The probability to detect deviations of measurement with such internally determined control rules is discussed.