Original scientific paper

https://doi.org/10.11613/BM.2018.020708

Sigma metrics for assessing the analytical quality of clinical chemistry assays: a comparison of two approaches

Xiuzhi Guo ; Department of Laboratory Medicine, Peking Union Medical College Hospital, Chinese Academic Medical Science and Peking Union Medical College, Beijing, P.R. China
Tianjiao Zhang ; National Center for Clinical Laboratories, Beijing Hospital, National Center of Gerontology, Beijing, P.R. China
Xuehui Gao ; Department of Laboratory Medicine, Peking Union Medical College Hospital, Chinese Academic Medical Science and Peking Union Medical College, Beijing, P.R. China
Pengchang Tingting You1, Qiong Wu3, Jie Wu1, Fang Zhao1, Liangyu Xia1, Ermu Xu1, Li ; Department of Laboratory Medicine, Peking Union Medical College Hospital, Chinese Academic Medical Science and Peking Union Medical College, Beijing, P.R. China
Tingting You ; Department of Laboratory Medicine, Peking Union Medical College Hospital, Chinese Academic Medical Science and Peking Union Medical College, Beijing, P.R. China
Qiong Wu ; Clinical Laboratory, Affiliated Hospital of Chifeng University, Inner Mongolia, P.R. China
Jie Wu ; Department of Laboratory Medicine, Peking Union Medical College Hospital, Chinese Academic Medical Science and Peking Union Medical College, Beijing, P.R. China
Fang Zhao ; Department of Laboratory Medicine, Peking Union Medical College Hospital, Chinese Academic Medical Science and Peking Union Medical College, Beijing, P.R. China
Liangyu Xia ; Department of Laboratory Medicine, Peking Union Medical College Hospital, Chinese Academic Medical Science and Peking Union Medical College, Beijing, P.R. China
Ermu Xu ; Department of Laboratory Medicine, Peking Union Medical College Hospital, Chinese Academic Medical Science and Peking Union Medical College, Beijing, P.R. China
Ling Qiu ; Department of Laboratory Medicine, Peking Union Medical College Hospital, Chinese Academic Medical Science and Peking Union Medical College, Beijing, P.R. China
Xinqi Cheng ; Department of Laboratory Medicine, Peking Union Medical College Hospital, Chinese Academic Medical Science and Peking Union Medical College, Beijing, P.R. China

Abstract

Introduction: Two approaches were compared for the calculation of coefficient of variation (CV) and bias, and their effect on sigma calculation,
when different allowable total error (TEa) values were used to determine the optimal method for Six Sigma quality management in the clinical laboratory.
Materials and methods: Sigma metrics for routine clinical chemistry tests using three systems (Beckman AU5800, Roche C8000, Siemens Dimension)
were determined in June 2017 in the laboratory of Peking Union Medical College Hospital. Imprecision (CV%) and bias (bias%) were calculated
for ten routine clinical chemistry tests using a proficiency testing (PT)- or an internal quality control (IQC)-based approach. Allowable total error from
the Clinical Laboratory Improvement Amendments of 1988 and the Chinese Ministry of Health Clinical Laboratory Center Industry Standard (WS/
T403-2012) were used with the formula: Sigma = (TEa − bias) / CV to calculate the Sigma metrics (σCLIA, σWS/T) for each assay for comparative analysis.
Results: For the PT-based approach, eight assays on the Beckman AU5800 system, seven assays on the Roche C8000 system and six assays on the
Siemens Dimension system showed σCLIA > 3. For the IQC-based approach, ten, nine and seven assays, respectively, showed σCLIA > 3. Some differences
in σ were therefore observed between the two calculation methods and the different TEa values.
Conclusions: Both methods of calculating σ can be used for Six Sigma quality management. In practice, laboratories should evaluate Sigma multiple
times when optimizing a quality control schedule.

Keywords

Six Sigma; proficiency testing; internal quality control; allowable total error

Hrčak ID:

201528

URI

https://hrcak.srce.hr/201528

Publication date:

15.6.2018.

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