Validation of Automated Fragmented Red Cell Count by the Sysmex XN-9000: Correlation With Microscopy and Impact of Microcytosis/Hypochromia.

INTRODUCTION

This study aimed to evaluate the analytical performance and screening performance of fragmented red cell (FRC) enumeration by the reticulocyte (RET) channel of the Sysmex XN-9000 automated hematology analyzer and to determine its correlation with manual microscopy with a specific focus on the confounding effects of microcytosis and hypochromia.

METHODS

Peripheral blood samples from 209 patients with anemia who had positive FRC% flagged by the analyzer and 200 healthy individuals were analyzed. The FRC percentage (FRC%) was measured both by the automated analyzer and by standard manual microscopy. Statistical analyses, including correlation studies, receiver operating characteristic (ROC) curve, and Bland-Altman agreement analysis, were performed.

RESULTS

The area under the ROC curve for instrument-measured FRC% was 0.927, indicating potential diagnostic screening performance. Using manual microscopy as the reference method, the correlation coefficient for FRC% measured by the RET channel was 0.66, indicating a moderate correlation between the two methods. Bland-Altman analysis revealed a mean bias of -0.91% (limits of agreement: -4.61% to 2.79%) with 78.9% of instrument results reading higher than microscopy. The upper reference limit for FRC% in the healthy cohort was established at 0.17%.

CONCLUSION

The automated FRC% measurement on the XN-9000 serves as an effective screening tool. However, confirmatory manual microscopic review remains essential for samples with positive automated results or those exhibiting abnormal MicroR% and Hypo-He% values.