Medical testing laboratories applying critical Sigma value to establish appropriate internal quality control schemes for quantitative tests
JIAO Fangyan1,2, ZHANG Yu1,2, ZOU Guoying1, JIANG Weiping1, XU Fei1
1. Brain Hospital of Hunan Province /The Second People's Hospital of Hunan Province, Changsha 410007, China; 2. Hunan Center For Clinical Laboratory, Changsha 410007, China
Abstract：Objective In order to avoid the possible lack of control or over-control in the design of internal quality control (IQC) scheme, an appropriate IQC scheme based on critical sigma value and meeting the quality control (QC) performance objectives was established for the Medical laboratory. Method By using QC software and office software, the probability of error detection (Ped) and the probability of false rejection (Pfr) of common QC rules were calculated when the system error ranged from 0 to 4.50s. The sigma metric graph and the operational process specifications (OPSpecs) charts were drawn. Results The critical sigma value was obtained when Ped was 90% and Pfr was less than 5%, and the appropriate QC scheme was obtained. The standardized OPSpecs charts were drawn when the analysis quality assurance was 90%. Conclusion The IQC scheme based on the critical sigma value can effectively ensure the Ped of the QC scheme and maintain a low Pfrfor the Medical laboratory, so as to prevent lack of control or over-control. It is not recommended to use only one level of QC material, which is not conducive to the use of QC rules, and can not provide quality assurance for low-medium sigma level tests.
2024, Vol. 21 
