# Comparison of Delta Total Nucleated Cells Assessed via Sysmex XT-2000iV and Sysmex XN-1000V in Effusions in Cats

## TL;DR

This study compares two automated hematology analyzers for evaluating cat effusions, finding similar classification accuracy despite differences in measurements.

## Contribution

The study demonstrates that the new Sysmex XN-1000V can replace the older model for feline effusion analysis without losing diagnostic accuracy.

## Key findings

- The new analyzer shows a proportional and constant bias compared to the old one.
- Despite the bias, both analyzers classify feline effusions with similar accuracy.
- A ΔTNC > 2.5 remains a reliable indicator for effusive FIP using both analyzers.

## Abstract

Laboratory evaluation of effusions in cats is mandatory to correctly classify them and as an aid for clinical diagnosis. An important tool is the evaluation of the difference (Delta) in the total nucleated cell count measured by the different channels of an automated hematology analyzer (Sysmex XT-2000iV), which can be particularly helpful for feline infectious peritonitis diagnosis. In this study, we compared the Delta values obtained with the new analyzer Sysmex XN-1000V to the ones obtained with the Sysmex XT-2000iV in effusions from cats with different pathologies. Despite a positive proportional and constant bias, similar accuracy for the classification of samples was found. Similar information may therefore be obtained with the use of the new analyzer in place of the old one.

The ratio of the nucleated cell counts (ΔTNC) provided by the Sysmex XT-2000iV DIFF and BASO channels has been proven to be useful in differentiating effusions in cats; in particular, a ΔTNC > 2.5 was found to have high accuracy for effusive FIP. The objective of this study was to compare the ΔTNC obtained with the Sysmex XT-2000iV and Sysmex XN-1000V on different types of effusions. Fresh effusions from cats were evaluated with both analyzers. WBC-BASO, WBC-DIFF, and ΔTNC-XT from the Sysmex XT-2000iV and TNC-WNR, TNC-WDF, and ΔTNC-XN from the Sysmex XN-1000V were recorded and compared. Forty-five feline effusions were collected. The results were not significantly different for all parameters evaluated. The Passing and Bablok regression analysis for ΔTNC-XT and ΔTNC-XN revealed a slope of 1.612 (95% CI 1.030 to 2.316) and an intercept of −0.744 (95% CI −1.591 to −0.120); the Bland–Altman difference plot showed a positive bias of 4.382 (p = 0.02). Despite the finding of a positive proportional and constant bias between ΔTNC-XT and ΔTNC-XN, evident especially at high ΔTNC values, samples were classified accordingly between the two analyzers when ΔTNC-XT cut-offs were used, allowing the same accuracy for the identification of suspected and compatible FIP samples.