Sigma metric used to evaluate the performance of haematology analysers: choosing an internal reference analyser for the laboratory

Introduction: The sigma metric offers a quantitative framework for evaluating process performance in clinical laboratories. This study aimed to evaluate the analytical performance of automated analysers in haematology laboratories, using the sigma metric to choose the best analyser as an internal reference analyser.Materials and Methods: internal quality control (IQC) data were collected for 6 months from SNCS, and the sigma value was calculated for 9 haematology analysers in the laboratory.Results: For the normal control level, a satisfactory mean sigma value >= 3 was observed for all of the studied parameters of all automated analysers. For the low control level, platelet (PLT) count by Instrument (Inst.) G performed poorly, with a mean sigma value <3. Inst. H, with all parameters' sigma values >4, performed best and was chosen as the internal reference analyser.Conclusion: The sigma metric can be used as a guide to choose the QC strategy and plan QC frequency. It can facilitate the comparison of the same assay performed by multiple systems.

Automated summary

The study evaluated the analytical performance of automated analysers in haematology laboratories using the sigma metric and selected the best analyser as the reference. The results showed that all parameters of the automated analysers met satisfactory levels at the normal control level. However, the platelet count by Instrument G performed poorly at the low control level, while Instrument H performed the best.