Evaluation of Quality Assurance in a New Clinical Chemistry Laboratory by Six Sigma Metrics

Introduction: Six sigma is a new tool in quality assurance widely applied in several industrial quality control processes including health care industry, especially in clinical laboratories. Aim: To evaluate retrospectively the quality in a new clinical biochemistry laboratory and to take corrective measures to improve the analytical performance on sigma scale. Materials and Methods: This study was undertaken in a new clinical biochemistry laboratory at a Government tertiary care level hospital for a period of six months from February to July 2018. Imprecision (CV) calculated from the Bio-Rad Internal Quality Controls (IQC) of both normal (L1) and abnormal (L2) levels for 16 most common analytes were run on Beckman Coulter AU5800 analyser and inaccuracy (peer bias) calculated from the Bio-Rad External Quality Assurance Scheme (EQAS). The Allowable Total Error (TEa) values taken from CLIA and Biological Variation (for D BIL) guidelines and authors calculated sigma metrics from the standard sigma equation, Sigma(sigma)=(TEa-bias)/CV. Windows 7, MS Excel was used for statistical analyses. Results: Authors got a similar sigma value for both the level of controls. Nine parameters out of 16, (albumin, aspartate transaminase, total cholesterol, creatinine, glucose, total protein, urea, phosphorus and calcium) are of sigma metrics <= 3.0 and 4 parameters (alanine transaminase, alkaline phosphatase, total bilirubin and uric acid) have sigma <= 5. Amylase had a s of >= 5 and only two out of 16 tests (direct bilirubin and HDL-C) achieved a sigma value of 6. Conclusion: Further steps were taken to implement QC strategies to improve the sigma metrics as per Westgard and Cooper guidelines.