The Evaluation of Analytical Performance of Immunoassay Tests by Using Six-Sigma Method

Open access


Background: The Six-Sigma Methodology is a quality measurement method in order to evaluate the performance of the laboratory. In the present study, it is aimed to evaluate the analytical performance of our laboratory by using the internal quality control data of immunoassay tests and by calculating process sigma values. Methods: Biological variation database (BVD) are used for Total Allowable Error (TEa). Sigma values were determined from coefficient of variation (CV) and bias resulting from Internal Quality Control (IQC) results for 3 subsequent months. If the sigma values are ≥6, between 3 and 6, and <3, they are classified as »world-class«, »good« or »un - acceptable«, respectively. Results: A sigma value >6 was found for TPSA and TSH for the both levels of IQC for 3 months. When the sigma values were analyzed by calculating the mean of 3 months, folate, LH, PRL, TPSA, TSH and vitamin B12 were found >6. The mean sigma values of CA125, CA15-3, CA19-9, CEA, cortisol, ferritin, FSH, FT3, PTH and testosteron were >3 for 3-months. However, AFP, CA125 and FT4 produced sigma values <3 for varied months. Conclusion: When the analytical performance was evaluated according to Six-Sigma levels, it was generally found as good. It is possible to determine the test with high error probability by evaluating the fine sigma levels and the tests that must be quarded by a stringent quality control regime. In clinical chemistry laboratories, an appropriate quality control scheduling should be done for each test by using Six-Sigma Methodology.

1. Coskun A. Six Sigma and laboratory consultation. Clin Chem Lab Med 2007; 45(1): 121-3.

2. Co kun A, Inal T, Unsal I, Serteser M. Six Sigma as a Quality Management Tool: Evaluation of Performance in Laboratory Medicine. Quality Management and Six Sigma 2010; 247-61.

3. Paolo C, Plebani M. Errors in a Stat Laboratory: Types and Frequencies 10 Years Later. Clin Chem 2007; 53(7): 1338-42.

4. Huysal K, Budak YU. Application of sigma metrics for the assessment of quality assurance using theMQ-2000 PT HbA1c analyzer. Biochem Med (Zagreb). 2015; 25(3): 416-20.

5. Westgard JO, Klee GG. Quality management. In: Burtis CA, Ashwood ER, Bruns DE, eds. Tietz textbook of clinical chemistry and molecular diagnostics St. Louis, MO: Elsevier Saunders, 2006: 485-529.

6. Hens K, Berth M, Armbruster D, Westgard S. Sigma metrics used to assess analytical quality of clinical chemistry assays: importance of the allowable total error (TEa) target. Clin Chem Lab Med 2014; 52(7): 973-80.

7. Rico’s C, Alvarez V, Cava F, et al. Desirable Specifications for total error, imprecision, and bias, derived from intraand inter-individual biologic variation. The 2010 update.

8. Ricos C, Alvarez V, Cava F, Garcia-Lario JV, Hernandez A et al. Current databases on biological variation: pros, cons and progress. Scand J Clin Lab Invest 1999; 59: 491-500.

9. Westgard JO, Westgard SA. Assessing quality on the Sigma scale from proficiency testing and external quality assessment surveys. Clin Chem Lab Med 2015; 53(10): 1531-5.

10. Schoenmakers CH, Naus AJ, Vermeer HJ, van Loon D, Steen G. Practical application of Sigma Metrics QC procedures in clinical chemistry. Clin Chem Lab Med 2011; 49(11): 1837-43.

11. Gras JM, Philippe M. Application of the Six Sigma concept in clinical laboratories: a review. Clin Chem Lab Med 2007; 45: 789-96.

12. Farr AJ, Freeman KP. Quality control validation, application of sigma metrics, and performance comparison between two biochemistry analyzers in a commercial veterinary laboratory. J Vet Diagn Invest 2008; 20(5): 536-44.

13. Westgard JO. Six Sigma quality design and control. Westgard QC, Inc, Madison.

14. Singh B, Goswami B, Gupta VK, Chawla R, Mallika V. Application of sigma metrics for the assessment of quality assurance in clinical biochemistry laboratory in India: a pilot study. Indian J Clin Biochem 2011; 26(2): 131-5.

15. Aslan D, Demir S. Six-Sigma Quality Management in Laboratory Medicine. Turk J Biochem 2005; 30 (4); 272-8.

16. Lakshman M, Reddy BR, Bhulaxmi P, Malathi K, Salma M et al. Evaluation of sigma metrics in a Medical Biochemistry lab. International Journal of Biomedical Research 2015; 6(03): 164-71.

17. Nanda SK, Ray L. Quantitative application of sigma metrics in medical biochemistry. J Clin Diagn Res 2013; 7(12): 2689-91.

18. Litten J, Lynne N, Johnson K, Shih J. Evaluation of technopath controls on the architect family of instruments. Clin Chem Lab Med 2015; 53, Special Suppl, pp S1-S1450.

19. Gulbahar O, Arslan B, Sen B, Cingirt M, Yılmaz SN. Evaluation of thyroid function tests in our laboratory by using six sigma analysis. Turkish Journal of Biochemistry 2015; 40 (S1).

20. Ercan M, Bogdaycıo lu N, Akbulut ED, O uz E, Top cuo lu C et al. Assessment of the analytic performance for immunassay tests with six sigma methodology. Clin Chem Lab Med 2015; 53, Special Suppl, pp S1-S1450.

21. Aksoy N, Tekin NH, Bireroğlu N, Serin NO. Application of sigma metrics for immunoassay tests. Clin Chem Lab Med 2014; 52, Special Suppl, pp S1-S1760.

22. Theodorson E. Quality assurance in clinical chemistry: a touch of statistics and a lot of common sense. J Med Biochem 2016; 35: 103-12.

23. US Adiga, Preethika A, Swathi K. Sigma metrics in clinical chemistry laboratory - A guide to quality control. Al Am een J Med Sci 2015; 8(4): 281-7.

24. Westgard S, Westgard QC. Six Sigma metric analysis for analytical testing processes. Vol. 4. Abbott MS-09-7907, 2009.

Journal of Medical Biochemistry

The Journal of Society of Medical Biochemists of Serbia

Journal Information

IMPACT FACTOR 2017: 1.378
5-year IMPACT FACTOR: 0.704

CiteScore 2017: 1.05

SCImago Journal Rank (SJR) 2017: 0.307
Source Normalized Impact per Paper (SNIP) 2017: 0.532


All Time Past Year Past 30 Days
Abstract Views 0 0 0
Full Text Views 487 478 36
PDF Downloads 234 234 24