ÁP DỤNG THANG SIGMA TRONG ĐÁNH GIÁ CHẤT LƯỢNG XÉT NGHIỆM TẠI KHOA SINH HÓA - BỆNH VIỆN BỆNH NHIỆT ĐỚI TRUNG ƯƠNG

Abstract

Objectives: Apply the sigma metric to evaluate the of the analytical performance of biochemical tests at
the National Hospital for Tropical Diseases to design a quality control (QC) strategy.
Subjects and methods:A cross-sectional descriptive study was conducted on 24 biochemical indicators on
Beckman Coulter AU400 and Roche Cobas C501 at the Biochemistry Department of the National Hospital
for Tropical Diseases from February 2022 to May 2022. Bias was calculated based on the results of RIQAS
external quality assessment (%DEV). The coefficient of variation was calculated using threemonths of
internal quality control measurements at two levels, and desirable specification derived from acceptance
limits for proficiency testing of CLIA (Clinical Laboratory Improvement Amendment) was used as the
quality goal. The sigma value for each biochemistry test was calculated using the above data. The internal
quality control scheme and measure improvements were adjusted according to the Westgard Sigma rules.
Results: The sigma value for almost biochemistry tests on Beckman Coulter AU400 and Roche Cobas
C501 for two quality control levels were greater than 3 (the minimum acceptable threshold) with the
corresponding ratio of 81.25% and 97.78%. Appropriate internal control scheme was selected for each
assay based on Westgard Sigma rules.
Conclusions: Sigma metrics is a rapid quality tool to assess the analytical performance of a clinical
chemistry laboratory. Thus, sigma metric analysis provides quantifiable data for the laboratory to design
an internal quality control scheme, indicate poor assay performance, and evaluate the efficiency of existing
laboratory procedures.