Application of Sigma Metrics for the Assessment and Modification of Quality Control in Clinical Chemistry Laboratory of Hospital for Tropical Diseases
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Abstract
Objective: This study aims to assess the quality control performance in clinical chemistry using sigma metrics and to compare sigma metrics after quality control improvements.
Methods: This study collected %CV data from IQC and % Bias from the EQA results derived from performance evaluation using sigma metrics. The obtained data were used to identify the cause for tests with low-sigma metrics and to improve quality. All results were used to conduct comparative studies.
Results: Twenty-five tests were used to improve the quality control using the sigma metrics. It was discovered that 19 tests before the quality control improvements were included in the world class performance (≥ 6-sigma) and excellent performance (≥ 5-sigma) criteria which can be used in the rules of 13s, (N = 2, R = 1) and 13s/22s, /R4s (N =2, R=1) respectively. After quality control improvement, tests with the world class and excellent performance was increased to 22 included; glucose, creatinine, uric acid, cholesterol, triglyceride, HDL, LDL, total protein, AST, ALT, ALP, CPK, LDH, amylase, GGT, magnesium, BUN, albumin, total bilirubin, calcium, phosphorous and potassium. There was only 1 test with <4-sigma, chloride, that was applied the maximum QC 13s / 2 of 32s / R4s / 31s / 8x (N = 2, R = 4)
Conclusion: The Cobas 6000 automatic analyzer (model C501) at the Clinical Chemistry Laboratory of Tropical Medicine Hospital has an excellent diagnostic performance with a high level of six-sigma which makes it possible to choose the suitable quality control rules for testing programs. Beneficially, six-sigma provides cost saving, convenience, and easy to apply. Moreover, using sigma matric helped to reduce the clinical testing workload. However, laboratory worker must follow the all test items. In addition, the training program recognizing of six-sigma is important. Therefore, staff should have knowledge and competence to select quality control rules and interpret the control result.
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References
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