Correlation of nucleated red blood cell counts by Sysmex XN-1000 with conventional microscopy

Abstract

Objective: To correlate the results of manual microscopy with that of Sysmex XN-1000 analyzers and to determine its diagnostic accuracy, taking microscopy as gold standard. Material and Methods: The study was conducted at Chughtai Institute of Pathology from July 1st -December 31st, 2022. Nucleated Red Blood Cells (nRBCs) were manually enumerated against 100 White Blood Cells (WBCs) on peripheral smears and 511 such positive cases were included. 500 samples negative for nRBCs by manual microscopy were also included. These positive and negative samples were run on two Sysmex XN-1000 analyzers. A result of 0.3 and above nRBCs/100 WBCs on Sysmex XN-1000 was considered positive and less than 0.3 as negative. Mean values of both manual and automated methods were correlated. Results: Our study mentioned nRBCs ranging from 0 to 1330 nRBCs/100WBCs by manual count. Compared with Sysmex XN-1000 analysis, the Deming regression analysis showed the mean difference between the two methods was 0.055 (95%CI: −0.015 to +0.124) (p>0.05 no proportional bias between two methods). The Sysmex XN produced an area under the curve, by ROC analysis, at 0.894 (P < .001). The overall sensitivity was (90.56%) (CI 87.56-92.98%), with few false-negative results. The overall specificity is (88.30%) (CI 85.20%-90.96%) due to few false positivity. Positive predictive value and negative predictive value were 88.26% (CI 88.54-90.52%) and 90.6% (CI 87.99-92.69%) respectively. Accuracy was 89.42% (CI87.35-91.25%). Conclusion: Sysmex XN1000 analyzer is a highly sensitive and accurate instrument which can replace nRBCs enumeration using manual counting by conventional microscopy. Keywords: Nucleated red blood cells, Hematology analyzer, Sysmex XN 1000, Manual microscopy