A comparison of the screening ability of two automated leukocyte differential counters.

The ability to screen out abnormal leukocyte differential counts by the H 6000TM and the Hematrak 590TM has been evaluated, using the visual 100 cell differential as a reference. Optimization of the discrimination levels for both instruments by the use of linear regression procedures and "Receiver Operating Characteristics (ROC) curves" and its impact on their performance characteristics is discussed. The overall sensitivity for 314 outpatient/188 inpatient samples was 0.84/0.94 for the H 6000 and 0.84/0.88 for the Hematrak, respectively. The overall specificities for out-/inpatient samples were found to be 0.61/0.44 and 0.47/0.30 for the H 6000 and the Hematrak, respectively. Both instruments had very similar screening abilities for the detection of abnormal leukocyte differential counts. However, the H 6000 flags correlated better with the visual findings than the Hematrak flags as demonstrated by the parameter-sensitivity and predictive value calculations and by the ROC curves.