APPLICATION OF THE SIX SIGMA METHOD IN QUALITY CONTROL OF PT, APTT, TT, AND FIBRINOGEN ASSAYS AT THE NATIONAL HOSPITAL OF ENDOCRINOLOGY DURING 2024–2025
Main Article Content
Abstract
Objective: Evaluation of Analytical Quality and Selection of Internal Quality Control Testing Frequency for PT, TT, aPTT, and Fibrinogen Assays on the ACL TOP 550 Analyzer at the National Hospital of Endocrinology (2024–2025).
Subjects and methods: A descriptive study was conducted on 3,480 internal quality control (IQC) results from four assays (PT, aPTT, TT, and Fibrinogen) at two concentration levels, performed once daily per level per assay, along with 72 external quality assessment (EQA) results from 18 samples performed monthly. All assays were analyzed on the ACL TOP 550 coagulation analyzer. CV% values were calculated from IQC data, Bias was determined from EQA results, and TEa values were referenced from CLIA and RCPA guidelines [1]. Sigma metrics were calculated using the formula: Sigma = (TEa – Bias)/CV. Based on Sigma values, appropriate Westgard rules and IQC frequencies were proposed.
Results: At the normal QC level, PT, aPTT, and TT achieved Sigma values of 5.6, 5.3, and 5.4, respectively (excellent performance), while Fibrinogen achieved a Sigma value of 3.0 (acceptable performance). At the abnormal low QC level, aPTT and TT reached Sigma values of 6.7 and 7.5, respectively (world-class performance), PT achieved 3.7, and Fibrinogen remained at 3.0. Based on Sigma metrics, aPTT and TT can apply simplified control rules with lower internal quality control (IQC) frequency, whereas PT and Fibrinogen require multirule QC procedures and increased IQC frequency.
Conclusion: Six Sigma is an effective tool for evaluating assay quality and guiding the development of laboratory quality control strategies. aPTT and TT demonstrated high and stable analytical performance, whereas Fibrinogen and PT at the abnormal low level required stricter quality control. Individualization of Westgard rules and IQC frequency contributes to improving the reliability of laboratory results and optimizing laboratory operations.
Keywords
Six Sigma, quality control, coagulation assays
Article Details
References
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