Evaluation of performance for automated differential leucocyte counting on Sysmex NE-8000 by NCCLS recommended protocol,H20-T

Summary In July and August 1989, the automated differential cell count (ADCC) capability of the Sysmex NE-8000 was evaluated by a modified H20-T protocol, the standard for differential leucocyte counting (DLC) method published by the National Committee for Clinical Laboratory Standards (NCCLS), USA. The ADCC of NE-8000 was compared with the manual reference method, using the Central Hematology Laboratory of the National Taiwan University Hospital as a venue. Of the total 493 blood samples analysed, 246 were from inpatients and 247, from outpatients. The NE-8000 system was found to be 4 to 4.5 times more precise than the 200-cell manual differential count in neutrophil, lymphocyte and eosinophil counts, and 1.5 to 2.5 times more precise in monocyte and basophil counts. According to our laboratory-defined criteria, the clinical sensitivity of NE-8000 was satisfactory with a sensitivity of 95.22%, a specificity of 83.71%, a false positive rate of 16.29%, a false negative rate of 4.78% and an efficacy of 95.10%. Correlation of the NE-8000 with the manual reference method was acceptable with correlation coefficients of 0.85 for neutrophils, 0.88 for lymphocytes, 0.97 for eosinophils, 0.62 for monocytes and 0.40 for basophils. The suspected interpretive messages given by the NE-8000 were good in flagging blasts and immature granulocytes only. In leucopenic specimens, the NE-8000 failed to flag morphological abnormalities in half of the cases. Traditional manual differential count of 100 or 200 leucocytes on stained smears also gave 2.3% false negative results on morphological anomalies. Generally speaking, it is practical to apply analysers which combine complete blood cell count and ADCC to deal with specimens without DLC abnormalities, and saving the manpower for those specimens with morphological abnormalities.