Two-site evaluation of the diagnostic performance of the Sysmex XN Body Fluid (BF) module for cell count and differential in Cerebrospinal Fluid

INTRODUCTION: Cellular analysis in cerebrospinal fluid (CSF) provides important diagnostic information in many pathological settings. The aim of this two-site study was to evaluate the Sysmex XN Body Fluid mode (XN-BF) for cell analysis of CSF compared to light microscopy (LM). METHODS: Two hundred and seven consecutive CSF samples were analyzed in parallel with XN-BF and LM. The study also included the estimation of the limit of blank (LoB), limit of detection (LoD), limit of quantitation (LoQ), carry-over and linearity of XN-BF module. RESULTS: LoQ of white blood cells (WBC) was 3×106 cells/L; linearity was good and carry-over negligible. XN-BF parameters were compared to LM for the following cell classes: total cells, WBC, polymorphonuclear (PMN), and mononuclear (MN) cells. The bias ranged from 1.3 to 15.2×106 cells/L. The receiver operating characteristics curve analysis for WBC showed an area under the curve of 0.98, and the global diagnostic agreement was 95% at a cutoff of 5×106 cells/L. CONCLUSIONS: XN-BF provides rapid and accurate counts in clinically relevant ranges of CSF values, thus providing a valuable alternative to conventional LM analysis. However, microscopic review remains advisable in samples with abnormal cell counts or high fluorescent (HF-BF) cell parameter exceeding 5×106 cells/L.