A short-term assessment of routine chemistry parameters using sigma metrics

Objectives: This study aims to improve the quality of our clinical laboratory by evaluating the performance of specific biochemical parameters on a sigma scale, identifying the reasons for poor performance, and taking corrective actions for those parameters. Material and Methods: This retrospective study confidently conducted data collection for quality control between June and November 2022. We derived Sigma metrics using “total allowable error (TEA),” “coefficient of variation (CV),” and “average bias” for biochemical parameters measured on the analyser, adhering to the Clinical Laboratories Improvement Amendments (CLIA). To pinpoint the sources of any issues, we generated the Quality Goal Index (QGI) for the analytes that displayed problems, ensuring a thorough understanding of the quality control process. Results: The initial maximum parameters perform < 3.0 demonstrated favourable sigma values. In contrast, Albumin, Alkaline Phosphate (ALP), alanine aminotransferase (ALT), Calcium, Chloride, Sodium, Potassium, Uria and Uric Acid yielded less satisfactory results. Furthermore, the Quality Goal index was evaluated for these parameters to ascertain whether the identified issues stemmed from imprecision, inaccuracy, or a combination of both. Conclusion: The findings indicate that sigma metrics effectively evaluate analytical performance in clinical biochemistry laboratories. Results suggest rigorous internal quality control (IQC) may not be necessary for parameters with sigma values between 3 and 6. However, before routine implementation, a thorough root cause investigation and performance enhancement are essential for any analyte with a sigma metric below 3.