Abstract:
Background: Clinical laboratories approve the validity of the analysis process according to
quality control procedures for each Clinical chemistry parameters. The sigma Metrics offer an
objective tool to inspect and judge on the performance of analytical quality control, and hence
select the suitable Westgard rule(s) to monitor the assay performance.
Objectives: To evaluate sigma metrics of commonly assayed clinical chemistry parameters at
Nekemte Specialized and Wellaga University Referral Hospitals Laboratory from September
2021 to February 2022.
Methods: A retrospective cross-sectional study was conducted to retrieved internal quality
control of 14 commonly assayed chemistry parameters for over a period of 6 months (September
2021 to February 2022) along with external QC result from one world accuracy. Excel 2010
software (Microsoft Corporation) was used for data analysis and graphing. Descriptive statistics
and Sigma value was analyzed using Total allowable error (TEa%),Bias% and CV% .
Result: Sigma values were calculated for both the levels of internal QC. At level one QC
solution; > 6 sigma were observed for HDL and UA. At level two QC solution; >6 sigma were
observed for BIL-T and TG. Four analytes (AST,BIL-T,CHOL-T and UA) showed between 3-5
sigma at L 1 and three analytes (AST, HDL and UA) at L2 QC, and out of 14 analytes 9 (ALT,
ALB, UREA, CREAT, LDL, TG, Na, Cl, K) showed < 3 sigma performance for both control
levels.
Conclusion: Sigma metrics results show poor performance laboratories in the quality control
processes. Thus strong quality control measures should be implemented to improve clinical
chemistry tests at the study sites. As sigma metrics is a good quality assessment tool, similar
studies should conduct to strengthen the QC & test results in other laboratories in the study
areas as well at the national level.
