Leukocyte screening using the ELT-800/WS.

In order to provide performance standards for instruments utilizing automated cell differentiation, a study was undertaken using the NCCLS Standard H20-T. The ELT-800/WS using light scattering technology was compared with a manual reference method. These were compared using normal values developed in the study for determination of sensitivity of the method, utilizing arbitration where necessary. Statistical analyses were performed including ANOVA, imprecision, sample size efficiency, and clinical sensitivity. Whereas the two methods (manual and automated) are quite different technologically, the mean differences are not significantly different for clinical purposes. The automated method is very precise. The normal values developed for the ELT 800/WS are comparable not only to the manual values developed by NCCLS but also to earlier values used for reference in the laboratory. In studies to identify or to classify samples as either normal or distributionally or morphologically abnormal, a false abnormal rate of 6.3% and a morphologically false abnormal rate of 8.7% were found. When the specific types are considered, in only two instances (3.2%) did the test method fail to show an operator alert with an abnormal specimen. The performance of the ELT-800/WS seems to be as accurate and as sensitive as the reference manual method and is satisfactory for clinical decision-making.