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

Abstract

The assessment of analytical efficiency  and quality control (QC) are important for

reliability 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 metric

for performance assessment and QC planning tools  in hematological and clinical chemistry

laboratory of Trang Hospital. Imprecision and inaccuracy of individual assays were calculated

from internal quality control (IQC) and proficiency testing (PT) or external quality assessment

(EQAS).  Sigma metric was calculated from (%TEa -  %bias) /  %CV to  assess laboratory

competency. A 6-month collective retrospective set of data obtained from October 2016 to March

2017  was analyzed in this study. Data analyses were performed on two analyzers; Beckman

Coulter (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 at

the  world  class  and excellent  performance  level.  Two  AU680  analyzers  were  operated  to

evaluate 26 laboratory items of clinical chemistry laboratory. The calculated sigma metrics have

shown that more than 80% of the evaluated parameters are ranked at world class and excellent

performance levels. The sigma metric results are categorized according to the rule of thumb and single 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 error detection 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 laboratory

needs to solve and improve the quality of result by increasing the frequency of calibration and quality control.