Quality Indicator-Driven Six Sigma Scale Assessment of Extra-Analytical Phases in Clinical Chemistry Laboratory-Insights from a Tertiary Care Hospital

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BACKGROUND: In recent years, the error rate in the analytical stage of laboratory testing has been drastically reduced due to automation, good-quality reagents, standardized assays, and increased participation of laboratories in proficiency testing programs. Nevertheless, high error rates in extra-analytical phase remains a critical vulnerability impacting diagnostic performance and patient safety. OBJECTIVE: The present observational study was designed to quantify error rates and evaluate efficiency of extra-analytical processes, using quality indicators on the Sigma metrics. METHODS: We examined extra-analytical errors in 51,072 test requests received in the Clinical Biochemistry Laboratory of GIPMER Delhi, India from March to August 2025. Extra-analytical phase quality standards for sample testing conformed to the IFCC quality indicators. Minitab software was used to calculate Six Sigma from the collected data. RESULTS: Our investigation revealed that 1572 errors, accounting for about 90% of the total, occurred during extra-analytical phase. Manual entry of test request information in the autoanalyzer during the pre-analytical stage and transcription of test results into patient reports in the post-analytical stage accounts for 35% of all laboratory errors in this study. Pre-analytical errors were chiefly Test transcription (39%), and haemolysis (27%); while post-analytic errors were delay in TAT (43%), and manual result entry errors (41%), expressed as percentage of total pre-analytical and post-analytical errors respectively. Sigma values for all QIs were acceptable ranging from 4-4.9 for the pre-analytical and 4.2-5 in the post-analytical processes of laboratory testing. CONCLUSION: Clinical biochemistry laboratories can significantly improve extra-analytical phase quality using Six Sigma based Quality Indicator framework.