Quantitative Assessment of Analytical Phase Quality of Clinical Biochemistry Parameters Using Sigma Metrics

Six sigma is the latest version of total quality management. It is quantitative goal for process performance. With increasing demands for improved accuracy and reliability of the results, Six Sigma is gaining increased visibility in the clinical laboratory process outcomes. The aim of study was to evaluate the quality of analytical phase performance in a clinical biochemistry laboratory by calculating sigma metrics.
The study was conducted in a hospital laboratory of Bhatia Hospital, Mumbai. Mean, coefficient of variation, bias, and sigma values were calculated for 24 biochemistry parameters. The guidelines used for total error allowable (TEa) values were clinical laboratory improvement amendments (CLIA), RILIBAK and college of american pathologists (CAP). Four months’ internal and external quality control data were extracted for the following parameters-albumin, alkaline phosphatase (ALP), alanine aminotransferase (ALT), amylase, aspartate aminotransferase (AST), bilirubin direct, bilirubin total, Ca, cholesterol, creatine kinase (CK), creatinine, triglycerides (TG), Uric acid (UA), unsaturated iron binding capacity (UIBC), urea, gamma-glutamyl transferase (GGT), glucose, high-density lipoproteins (HDL), iron, lactate dehydrogenase (LDH), lipase, Mg, phosphorus and total protein.
Albumin, ALP, AST, ALT, amylase, bilirubin total, Ca, cholesterol, CK, creatinine, TG, uric acid, GGT, glucose, iron, LDH, lipase, Mg, Phosphorus, total protein showed the performance of more than six Sigma for both level of controls. Bilirubin direct, Urea, for level 1; UIBC, urea, HDL for level 2 showed sigma from 3-6.
Based upon sigma metrics, laboratory quality control strategy can be planned and reevaluated for continuous monitoring and improvement of test methods.