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From kit inserts to daily practice: Six sigma and maximum allowable uncertainty in coagulation analysis
1Department of Medical Biochemistry, Umraniye Training and Research Hospital, Istanbul, Turkey.
Medicine
|October 7, 2025
Summary
This study evaluated the Sysmex CS-2500 coagulation analyzer
Area of Science:
- Clinical Chemistry
- Laboratory Medicine
- Medical Diagnostics
Background:
- Accurate laboratory test results are critical for effective patient care.
- Manufacturers provide performance metrics, but daily laboratory precision can be challenging.
- Routine analytical performance assessment is essential for diagnostic accuracy.
Purpose of the Study:
- To compare the analytical performance of the Sysmex CS-2500 coagulation analyzer in routine use against manufacturer specifications.
- To evaluate the analyzer's precision using Six Sigma and Measurement Uncertainty (Mu) methods.
- To identify potential bias-related limitations in daily laboratory settings.
Main Methods:
- Data collected from June to November 2024 at Ümraniye Training and Research Hospital.
- Coagulation tests (PT, INR, aPTT) assessed via internal quality control and external quality assessment.
- Six Sigma metrics calculated per CLIA 2024; Maximum Allowable Uncertainty (Mu) derived from biological variation data.
Main Results:
- SigmaLAB scores were ≥5, except in July due to external quality assessment bias.
- SigmaMD scores consistently remained >6.
- Mu analysis revealed PT and INR fell below minimum specifications in MuLAB at times, while aPTT met desirable limits; MuMD showed PT within minimum, INR borderline, and aPTT borderline optimal limits.
Conclusions:
- Six Sigma offers retrospective performance insights, while Measurement Uncertainty (Mu) enables continuous monitoring.
- Combining Six Sigma and Mu provides a comprehensive assessment of analyzer performance.
- Field results indicated bias-related limitations despite strong manufacturer data, highlighting the need for ongoing performance evaluation.
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