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

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.