Overcoming Platelet Aggregation Interference: Evaluation of the Complete Blood Count, Differential, and Reticulocyte (CDR) Mode on an Automated Analyzer for Accurate Platelet Counting.

BACKGROUND

This study assessed the ability of the complete blood count, differential, and reticulocyte (CDR) mode of the Mindray BC-6800 Plus analyzer to correct platelet aggregation by disaggregating platelets, evaluating how aggregation severity impacts accuracy to define an objective threshold for resampling.

METHODS

Agreement was assessed between CDR mode and the electrical impedance method for platelet counts in normal specimens using Pearson correlation, Passing-Bablok regression, and Bland-Altman analysis. The CDR mode's ability to correct false elevations caused by microcytes/fragments and false reductions caused by large platelets was evaluated by comparing CDR channel platelet count results (PLT-OF) with smear-estimated values (PLT-M) and fluorescence-method results (PLT-F). Disaggregation efficacy in aggregated samples was analyzed using the MC-80 digital morphology system. The optimal disaggregation threshold was determined by ROC analysis.

RESULTS

In normal specimens, PLT-OF showed a significant correlation with the electrical impedance-method platelet count results (PLT-I) (r = 0.999, P < 0.001). Passing-Bablok regression (PLT-I = 1.00 × PLT-OF) and Bland-Altman analysis demonstrated excellent agreement. For samples with PLT-I false abnormalities, the CDR mode effectively corrected both false elevations (due to microcytes/fragments) and false reductions (due to large platelets), showing no significant differences between PLT-OF and PLT-M or PLT-F (P > 0.05). In platelet-aggregated specimens, PLT-OF was significantly higher than PLT-I (P < 0.001). ROC analysis established 162 aggregates as the optimal threshold for effective disaggregation [area under the curve (AUC) = 0.776]. The dissociation rate was significantly greater in the mild vs severe-aggregation group (P = 0.004). Combining aggregate count with a PLT-OF to PLT-I difference (>115 × 109/L) improved prediction accuracy (AUC = 0.841).

CONCLUSION

The CDR channel of the Mindray BC-6800 Plus analyzer effectively corrects spurious platelet counts.