Establishment of an assigned value and its uncertainty for tumour markers in proficiency testing in China

Abstract

Proficiency testing (PT) is an important aspect of clinical laboratory quality control for tumour markers. To evaluate the performance of an individual laboratory, the assigned value and the standard uncertainty of each tumour marker must be determined. However, no data about the standard uncertainty of the assigned value of any analyte in PT is available in China. The aim of this paper is to introduce a new approach for establishment of assigned value and its standard uncertainty for tumour markers. Five sets of control materials at different concentrations were assigned to each laboratory that participated in PT for tumour markers in 2012. We collected the data from each laboratory using the Clinet-EQA reporting system V1.5 and Clinet-EQA evaluation system V1.0 and developed a software program to calculate the assigned value and its uncertainty according to ISO 13528 (Statistical methods for use in proficiency testing by interlaboratory comparisons. ISO 13528. International Standards Organisation, Geneva, 2005). The assigned value and inter-laboratory CV calculated by the new approach was compared with that obtained by the current approach used in PT in our country. No significant difference between the two outcomes was found in our study. Most assigned values had a standard uncertainty that can meet the criterion: \( u_{X} \le \, 0.3\hat{\sigma } \), which meant the new approach for establishment of the assigned value was acceptable. It is expected that the new approach to determination of the assigned value and its standard uncertainty for PT for tumour markers in China will enable participants to evaluate their measurement uncertainty.