Original article / research
Sigma Metrics-Tool for Quality Assurance in Clinical Biochemistry Lab
Vanitha Gowda MN,
MSR Nagar, Bengaluru, Karnataka, India.
Introduction: Sigma metrics is a quality management tool used for process improvement which usually comes into application when there is a measurable outcome in the process. It can play an important role in health care laboratory services as Quality Assurance (QA) of the same, is the need of the hour.
Aim: To gauge the performance of a few biochemical parameters by calculating their sigma metrics on a sigma scale.
Materials and Methods: This retrospective study was undertaken using Quality Control (QC) and External QA Scheme (EQAS) data for 17 biochemical parameters from Biochemistry section, diagnostic laboratory of an in-study institution. Sigma values for these parameters were determined and sigma metrics was evaluated for duration of months.
Results: In level 1 coefficient of variation percentage (CV%), five parameters (ALP, calcium, magnesium, triglycerides and HDL-cholesterol) showed an ideal performance of ≥6 sigma level and in level 2 CV%, eight parameters (total bilirubin, urea, creatinine, albumin, AST, total cholesterol, total protein and phosphorus) showed a sigma of ≥6. Quality Goal Index (QGI) for 10 analytes in level 1 and seven analytes in level 2 was <0.8, indicating imprecision. QGI was in the range of 0.8-1.2 for one analyte in level 1 and three analytes in level 2, indicating a problem of both imprecision and inaccuracy.
Conclusion: Sigma metric analysis can serve as a tool to identify the poor assay performance and to assess the efficiency of processes that are in existence. The health care sector can be immensely benefited by implementation of sigma metrics for QA.
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