Implementation of Sigma Metrics for Evaluation of Analytical Quality in Clinical Biochemistry Laboratory of a Tertiary Care Hospital

Abstract

BACKGROUND Amelioration of analytical quality in clinical laboratories is recognised as an emerging concern worldwide. Quality has been described as conformance to the requirement of users and the satisfaction of their needs and expectations. Quality assurance is need of the hour in all sectors including laboratory service. Six sigma provides a general methodology to describe performance on sigma scale. The present study was undertaken to evaluate the quality of the analytical performance of clinical biochemistry laboratory with the help of sigma metrics. MATERIALS AND METHODS Internal quality control (QC) data for both levels of control, L1 (normal) and L2 (high) obtained from clinical biochemistry laboratory of College of Medicine and Sagore Dutta Hospital were analysed over a period of one year from July 2016 to July 2017. Laboratory mean, standard deviation(SD) and coefficient of variation (CV %) were calculated for parameters like sugar, urea, creatinine, triglyceride, cholesterol, High Density Lipoprotein (HDL), Bilirubin, Aspartate Aminotransferase (AST), Alanine Aminotransferase (ALT), Alkaline Phosphatase (ALP), total protein, albumin and uric acid. Sigma factor was calculated using both levels of internal QC for the above-mentioned parameters. RESULTS Parameters such as ALP, Triglyceride (L2) and HDL with average sigma values (> 6) was considered as satisfactory. Parameters having average Sigma 3-6 relating to glucose, urea, creatinine (L2), ALT (L2), AST (L2), uric acid, Bilirubin total, Cholesterol (L1), Total protein and albumin were considered as acceptable, but needed close supervision. We got sigma < 3 for parameters like ALT (L1), AST (L1), Creatinine (L1) and Cholesterol (L2) which were unacceptable. CONCLUSION Sigma metrics thus calculated can be used as a guide for planning quality control strategy. The findings of our study will emphasise the need for evaluation of ongoing quality assurance programme and adoption of corrective and preventive measure. Ideal analytical methodology, quality control material and quality control strategy should be introduced to achieve uniform six sigma standards across all laboratories.