Performance evaluation of routine analytes using six sigma principle in a stand-alone clinical laboratory

Abstract

Sigma metrics of analytes based on data generated from IQC and EQAS is a reliable way of assessing and improving quality performance in the clinical laboratory. This study was undertaken to assess the sigma metrics of analytes used on a routine basis on a VITROS integrated analyser. Steps to improve quality based on the IQC and EQAS results was done monthly, based on QGI scores. The average sigma metrics at the end of year was compared with subsequent year. Data is presented for this comparison for four consecutive years between April 2017 to March 2021. 75% of analytes (12 out of 16) performed ≥ six sigma level on the current analyser in 2020-21, while 25% to 57% of routine analytes performed ≥ six sigma across published studies cited. Tests used for diagnostics which have high severity risk index such as Sodium, Creatinine, Glucose, Calcium and Uric Acid, all except Sodium had average sigma scores of more than six in VITROS 5600 analyzer used in this laboratory. On comparing performance of these important analytes across studies cited here, it was noticed that creatinine was a differentiator in this study which consistently performed at >6 sigma while in five of six studies cited the sigma score is less than six. In the context of the revised CLIA guidelines in 2019 wherein TE(a) for ten routine analytes have been reduced, it was noticed that with the lowering of TE(a) for many of these analytes, except uric acid, Triglycerides and AST, the performance shifted from > six sigma to a sigma lower than six.