Comparative analysis of platelet counts using Beckman Coulter DxH-900, Mindray BC-6800 Plus, CellaVision DM9600 and the flow cytometry reference method: Addressing the challenge of giant platelets

Abstract

Objectives: To evaluate the analytical performance of platelet counts obtained by impedance- and optical-based methods on the DxH-900 and BC-6800 Plus analyzers, and by digital morphology using the CellaVision DM9600, in comparison with the international reference method (IRM), in samples with thrombocytopenia and both normal-sized and giant platelets. Methods: Platelet counts were analyzed in peripheral blood samples from patients with thrombocytopenia and normal platelet counts, including cases with normal-sized and giant platelets. Each sample was tested using two automated analyzers: the DxH-900 (impedance) and the BC-6800 Plus (impedance and optical). Results were compared with the IRM based on flow cytometry, performed on the DxFlex analyzer. Precision was assessed. The methods were compared by Passing-Bablok regression and bias calculation. Additionally, platelet morphology was reviewed digitally using CellaVision DM9600. Results: All methods demonstrated high precision and strong correlation with IRM in samples with normal-sized platelets. However, significant discrepancies were observed in the presence of giant platelets. Impedance methods showed higher imprecision (CV>10%) and underestimated platelet counts with a negative bias exceeding -25%. Conversely, the optical method showed better correlation (r=0.9888) and precision (CV=1.6%), although it overestimated counts with a positive bias of 19.4%. Digital morphology also demonstrated strong agreement with IRM. Conclusions: These findings highlight the analytical limitations of routine technologies in challenging samples and emphasize the importance of method selection for accurate platelet reporting. A correction factor for optical counts and the integration of digital morphology could enhance diagnostic reliability in cases involving giant platelets.