Evaluation on clinical performance of the new low-value platelet measurement mode (PLT-8X) of BC-6800Plus

Background: The accuracy of low-value platelet (PLT) testing is a key reference for clinical decision-making regarding PLT transfusion or surgery. This study aimed to evaluate the capability to detect low-value PLT of the 8 times optical platelet counting (PLT-8X) mode of the BC-6800Plus auto hematology analyzer. Methods: Totally 40 fresh anticoagulated venous whole blood samples with PLT <= 5.50x10(9)/L. were collected from the clinical laboratory at the First Affiliated Hospital of Soochow University to evaluate the precision of low-value PLT in PLT-8X mode. Moreover, 67 samples with PLT <100x10(9)/L were collected, and a methodological comparison was conducted between the results of PLT-8X and those obtained by the reference method [red blood cell (RBC)/PLT ratio method] recommended by the International Committee for Standardization of Hematology (ICSH). In addition, fresh whole blood and PLT-free plasma were used to prepare samples at a series of concentrations within the low-value ranges to evaluate the linearity of PLT and finally investigate the limit of blank (LoB) and limit of detection (LoD) for low-value PLT in PLT-8X mode. Results: The precision low-value PLT in PLT-8X mode was significantly superior to that in PLT-I (P<0.0001); and the correlation coefficient of PLT-8X mode compared with the reference method of flow cytometer was 0.992. The expected bias at the low-value medical decision levels (5x10(9)/L, 10x10(9)/L and 20x10(9)/L) of PLT fell within the range of +/- 1.0x10(9)/L, and that at 50x10(9)/L fell within the range of +/- 1.5x10(9)/L. In addition, the correlation coefficient of PLT-8X in the low-value ranges (0 to 30x10(9)/L and 0 to 100x10(9)/L) of PLT was greater than 0.99, and its nonlinear coefficients were not significantly different from 0 (P>0.05). Finally, the LoB and LoD of PLT-8X mode were 0.33x10(9)/L and 0.89x10(9)/L, respectively. Conclusions: The PLT-8X mode of the BC-6800Plus auto hematology analyzer has extremely low detection sensitivity for low-value PLTs in anticoagulated venous whole blood samples. With good linearity, its precision and accuracy can sufficiently meet the needs for hematology laboratory use, and it can effectively help clinicians to accurately diagnose and treat patients with thrombopenia-related diseases.