Attempt to establish a control range using CVs calculated from past internal quality control measurements

Abstract

Act on Clinical Laboratory Technicians was amended by the Medical Care Act promulgated on June 14, 2017. This clarified the standards for accuracy control at medical institutions and registered health laboratories that provide specimen testing services. According to a 2017 report, more than 90% of facilities that perform biochemical testing have internal quality control (IQC). Therefore, each laboratory measures samples of known concentration for accuracy control and confirms their accuracy. When a control sample is changed to a new lot, it is usually necessary to measure the current and new lot control samples in parallel for about one month to set a new control range, which is time-consuming and costly. In this study, when a controlled sample is changed to a new lot, we devised a method to set a control width for the new lot without spending time and money. Methods and Results: (1) There was no difference in the precision of QAP trawls from different lots. (2) The Bonferroni method was used to compare monthly IQC measurements, and significant differences were found among most of the groups. (3) The CV variability was reduced by aggregating IQC measurements over 6 months. Based on the above, we believe that this method can be used at many facilities because it is relatively easy and cost-effective for facilities that have conducted IQC and accumulated IQC data to calculate the SD relative to the target value using the CV calculated from IQC measurements for a minimum of 6 months.