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. 2022 Feb 15;32(1):010703.
doi: 10.11613/BM.2022.010703. Epub 2021 Dec 15.

Evaluation of the clinical chemistry tests analytical performance with Sigma Metric by using different quality specifications - Comparison of analyser actual performance with manufacturer data

Murat Keleş  1
Affiliations

Evaluation of the clinical chemistry tests analytical performance with Sigma Metric by using different quality specifications - Comparison of analyser actual performance with manufacturer data

Murat Keleş. Biochem Med (Zagreb). .

Abstract

Introduction: The interest in quality management tools/methodologies is gradually increasing to ensure quality and accurate results in line with international standards in clinical laboratories. Six Sigma stands apart from other methodologies with its total quality management system approach. However, the lack of standardization in tolerance limits restricts the advantages for the process. Our study aimed both to evaluate the applicability of analytical quality goals with Roche Cobas c 702 analyser and to determine achievable goals specific to the analyser used.

Materials and methods: The study examined under two main headings as Sigmalaboratory and Sigmaanalyser. Sigmalaboratory was calculated using internal and external quality control data by using Roche Cobas c 702 analyser for 21 routine biochemistry parameters and, Sigmaanalyser calculation was based on the manufacturer data presented in the package inserts of the reagents used in our laboratory during the study. Sigma values were calculated with the six sigma formula.

Results: Considering the total number of targets achieved, Sigmaanalyser performed best by meeting all CLIA goals, while Sigmalaboratory showed the lowest performance relative to biological variation (BV) desirable goals.

Conclusions: The balance between the applicability and analytical assurance of "goal-setting models" should be well established. Even if the package insert data provided by the manufacturer were used in our study, it was observed that almost a quarter of the evaluated analytes failed to achieve even "acceptable" level performance according to BV-based goals. Therefore, "state-of-the-art" goals for the Six Sigma methodology are considered to be more reasonable, achievable, and compatible with today's technologies.

Keywords: Six Sigma; biological variation; quality control; total allowable error.

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Conflict of interest statement

Potential conflict of interest None declared.

Figures

Figure 1
Figure 1
Our Laboratory “Normalized Sigma-metric Method Decision Chart” according to CLIA goals. Alb - Albumin. ALP - Alkaline phosphatase. ALT - Alanine aminotransferase. Amy - Amylase. AST - Aspartate aminotransferase. DBIL - Bilirubin, direct. TBIL - Bilirubin, total. Ca - Calcium. Chol - Cholesterol. Cl - Chloride. Crea – Creatinine. GGT - Gamma-glutamyltransferase. Glc - Glucose. HDL - High-density lipoprotein cholesterol. LD - Lactate dehydrogenase. K - Potassium. TP - Total protein. Na - Sodium. TG - Triglycerides. UA - Uric acid. ● – Unacceptable. ■ – Poor. ▲ – Good. ♦ - Marginal. - Excellent. - World Class.
Figure 2
Figure 2
Our Laboratory “Normalized Sigma-metric Method Decision Chart” according to desirable BV goals. . Alb - Albumin. ALP - Alkaline phosphatase. ALT - Alanine aminotransferase. Amy - Amylase. AST - Aspartate aminotransferase. DBIL - Bilirubin, direct. TBIL - Bilirubin, total. Ca - Calcium. Chol - Cholesterol. Cl - Chloride. Crea – Creatinine. GGT - Gamma-glutamyltransferase. Glc - Glucose. HDL - High density lipoprotein. LD - Lactate dehydrogenase. K - Potassium. TP - Total protein. Na - Sodium. TG - Triglycerides. UA - Uric acid. ● – Unacceptable. ■ – Poor. ▲ – Good. ♦ - Marginal. - Excellent. - World Class.
Figure 3
Figure 3
Roche Cobas c 702 reagent package insert’s “Normalized Sigma-metric Method Decision Chart” according to CLIA goals. Alb - Albumin. ALP - Alkaline phosphatase. ALT - Alanine aminotransferase. Amy - Amylase. AST - Aspartate aminotransferase. DBIL - Bilirubin, direct. TBIL - Bilirubin, total. Ca - Calcium. Chol - Cholesterol. Cl - Chloride. Crea – Creatinine. GGT - Gamma-glutamyltransferase. Glc - Glucose. HDL - High density lipoprotein. LD - Lactate dehydrogenase. K - Potassium. TP - Total protein. Na - Sodium. TG - Triglycerides. UA - Uric acid. ● – Unacceptable. ■ – Poor. ▲ – Good. ♦ - Marginal. - Excellent. - World Class.
Figure 4
Figure 4
Roche Cobas c 702 reagent package insert’s “Normalized Sigma-metric Method Decision Chart” according to BV goals. Alb - Albumin. ALP - Alkaline phosphatase. ALT - Alanine aminotransferase. Amy - Amylase. AST - Aspartate aminotransferase. DBIL - Bilirubin, direct. TBIL - Bilirubin, total. Ca - Calcium. Chol - Cholesterol. Cl - Chloride. Crea – Creatinine. GGT - Gamma-glutamyltransferase. Glc - Glucose. HDL - High density lipoprotein. LD - Lactate dehydrogenase. K - Potassium. TP - Total protein. Na - Sodium. TG - Triglycerides. UA - Uric acid. ● – Unacceptable. ■ – Poor. ▲ – Good. ♦ - Marginal. - Excellent. - World Class.
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References

    1. Carter P. Report of the Review of NHS Pathology Services in England. Available from: https://www.networks.nhs.uk/nhs-networks/peninsula-pathology-network/doc.... Accessed April 27th 2021.
    1. Hallworth MJ. The “70% claim”: what is the evidence base? Ann Clin Biochem. 2011;48:487–8. 10.1258/acb.2011.011177 - DOI - PubMed
    1. Aslan D, Demir S. Six-Sigma Quality Management in Laboratory Medicine. Turk J Biochem. 2005;30:272–8. [in Turkish]
    1. Nevalainen D, Berte L, Kraft C, Leigh E, Picaso L, Morgan T. Evaluating laboratory performance on quality indicators with the six sigma scale. Arch Pathol Lab Med. 2000;124:516–9. 10.5858/2000-124-0516-ELPOQI - DOI - PubMed
    1. Westgard JO. Six sigma quality design and control: Desirable precision and requisite QC for laboratory measurement processes. Madison, WI: Westgard QC; 2001.