Flagging performance of two automated hematology analyzers in blast cell screening

With the rapid development of automated hematology analyzers, hematology analyzers have gradually become routinely adopted in hematology laboratories, with improved efficiency and accuracy. To enable the laboratory to review specific blood specimens selectively and to significantly improve the efficiency and quality of clinical laboratories, the capability of hematology analyzers to identify and flag abnormal cells has become one of the most critical links (1). Whether there are blast cells in peripheral blood (PB) is of great value for clinical screening and monitoring of the occurrence and progression of hematological malignancies (2,3). For hematological malignancies, early diagnosis and treatment are beneficial to patients’ long-term survival (4,5). Therefore, the sensitivity of hematology analyzers for the detection of blast cells has become a focus of hematology laboratories. We carried out comparative adding experiments of blast cells with 2 automated hematology analyzers (Mindray BC-7500CRP, Sysmex XN-1000) in our laboratory to compare their flags for blast cells and evaluated the blast flagging capability of the 2 hematology analyzers, with the microscopic results of blast cells as the quantitative gold standard. In this study, 16 cases of EDTA-K2-anticoagulated venous whole blood specimens from the clinical laboratory of Fujian Medical University Union Hospital were collected from June 2020 to August 2020, including 11 cases of acute myeloid leukemia (AML) and 5 cases of acute lymphoblastic leukemia (ALL). Specimens from 10 healthy controls with the same blood grouping were collected as the base pool. The volume of each anticoagulated whole blood specimen was not less than 1.5 mL, and the experiment was completed within 8 h after collection. The instruments and supporting reagents used in this study were the Mindray BC-7500CRP automated hematology analyzer and supporting calibrators, quality controls, and reagents (Mindray, Shenzhen, China); the Mindray SC-120 automated blood smear preparation instrument and supporting reagents (Shenzhen Mindray, China); and the Sysmex XN-1000 automated hematology analyzer and supporting reagents (Sysmex, Kobe, Japan). When the blast cell is detected, the instrument will generated by the instrument. The microscopic results of blast cells is performed by two clinical pathologists with ample experience in morphology, who observed and recorded the morphological features of various blood cells. Blood specimens containing a series of concentration gradients of blast cells were prepared in this study and detected in parallel on 2 hematology analyzers. The concentration points of blast cells that were flagged by the instruments were summarized and the detection thresholds were calculated. The specific operating procedures were described in Appendix 1. The minimum Blast% and Blast# results of the 2 instruments from their “blast” flags were expressed as median (P25–P75) and were statistically analyzed with Prism v8.2.1 (GraphPad). The quantitative data of the 2 groups were compared using the Wilcoxon signed rank test for paired samples. P<0.05 indicated statistical significance. In the 16 groups of experimental data (Figure 1), the sensitivities of the 2 instruments in blast cell screening had their own advantages and disadvantages. Paired statistical analysis showed that the results of Blast# and Blast% at the minimum threshold of the Mindray BC-7500CRP were 0.09×10/L (0.04×10/L–0.16×10/L) and 1.4% 1606