Assessment of Hematology and Clinical ChemistryLaboratory Performance by Six Sigma Metric; Department of Medical Technology, Trang Hospital

Tassanee Sirithansaul


The assessment of analytical efficiency and quality control (QC) are important forreliability of laboratory results. Maximum benefits given for patients are accurate laboratory results with suitable quality control in clinical laboratory. This study aimed to use sigma metricfor performance assessment and QC planning tools in hematological and clinical chemistrylaboratory of Trang Hospital. Imprecision and inaccuracy of individual assays were calculatedfrom internal quality control (IQC) and proficiency testing (PT) or external quality assessment(EQAS). Sigma metric was calculated from (%TEa - %bias) / %CV to assess laboratorycompetency. A 6-month collective retrospective set of data obtained from October 2016 to March2017 was analyzed in this study. Data analyses were performed on two analyzers; BeckmanCoulter (LH780) automatic blood cell counting analyzer and Beckman Coulter (AU680) clinical chemistry analyzers. LH780 was routinely operated to determine platelet count (PLT), red blood cell count (RBC), hemoglobin concentration (HGB) and mean cell volume (MCV) parameters atthe world class and excellent performance level. Two AU680 analyzers were operated toevaluate 26 laboratory items of clinical chemistry laboratory. The calculated sigma metrics haveshown that more than 80% of the evaluated parameters are ranked at world class and excellentperformance levels. The sigma metric results are categorized according to the rule of thumb andsingle rule 13S, N=2 (Pfr < 0.01, Ped 90) was selected as quality control for the majority of analyzed parameters. This has been shown to be an appropriate and flexible rule with high errordetection capability and low false rejection rate for clinical laboratory. By using sigma matric,we have controlled cost effectiveness of quality control planning and a reduction of workload.However, the sigma analysis of WBC, low-density lipoprotein (LDL), blood urea nitrogen (BUN)and total protein (TP) has shown marginal performance. In this circumstance, the laboratoryneeds to solve and improve the quality of result by increasing the frequency of calibration andquality control.

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