Application of Six Sigma Metrics to Analyze the Performance of Internal Quality Control in Hematology Laboratory

Abstract Introduction: Clinical laboratories play a crucial role in patient diagnosis, which in turn affects treatment and management. Hence, it is important to give accurate and precise laboratory results. Even though advancements and automation have reduced analytical errors, it is better to have random checks of our Internal Quality Control (IQC) data to ensure the authenticity of laboratory reports. The aim of this study was to analyze the performance of IQC of various parameters of CBC (hemoglobin [Hb], red blood cell count [RBC], hematocrit [HCT], white blood cell count [WBC], and platelet count [PLT]) using the sigma metric method. Materials and Methods: This was a prospective observational study conducted over a period of 6 months in a tertiary care center. All IQC of 3 levels which has been run in the Sysmex XN-1000 5-part Hematology Analyzer in our Hematology Laboratory was included in this study. We calculated sigma metrics of five important parameters of CBC – Hb, RBC, HCT, WBC, and PLT. Results: Sigma value was >6 for Hb, RBC, WBC, and PLT, which indicates world-class results and thus does not require any modification in IQC. The sigma value falls between 3 and 4 only for HCT, which indicates marginal to good results, where there can be scope for improvement. No analytes showed sigma value <3, thus indicating all the results are in an acceptable range. Conclusion: Application of sigma metrics is considered to be an efficient self-assessment tool to analyze the performance of IQC in laboratories.