Department of Clinical Biochemistry, Nordsjaellands Hospital, University of Copenhagen, Copenhagen, Denmark.
Department of Technology, Faculty of Health and Technology, University College Copenhagen, Copenhagen, Denmark.
Int J Lab Hematol. 2024 Apr;46(2):312-321. doi: 10.1111/ijlh.14204. Epub 2023 Nov 20.
Immature granulocyte percentage (IG%) is an important biomarker for infection control. We observed spurious cases where the IG% was dramatically underestimated on the automated Sysmex XN-series hehmatology analyzer compared with manual differential. These cases were associated with high values of "Neutrophil Reactivity Intensity" (NEUT-RI), which should reflect the metabolic activity of the neutrophils.
We conducted a three-stage study to evaluate whether NEUT-RI could be utilized to screen for misclassified IG% results defined as the manual differential estimating a 10 percentage points higher IG% compared with the automated Sysmex differential. First, 124 patient samples were selected for 800-cell manual smear analysis based on their NEUT-RI values and compared with the automatic Sysmex IG% results. Next, 11 098 routine 110-cell manual smear analyses were compared with the corresponding Sysmex IG% results. Finally, during a 19-day period 160 additional patient samples underwent smear based on NEUT-RI values ≥56 fluorescence intensity (FI) to screen for misclassified results beyond our current smear practice.
NEUT-RI ≥56 predicted IG% misclassification with 91% sensitivity and 88% specificity, but primarily when the internal Sysmex flag "Abnormal WBC Scattergram" was present. 90.1% of misclassified results were identified by this flag. Beyond our existing smear rules including this flag, NEUT-RI ≥56 FI had a positive predictive value below 1%.
Both NEUT-RI and the internal Sysmex flag "Abnormal WBC Scattergram" work well to identify cases of IG% misclassification. However, in our setting NEUT-RI ≥56 FI had no meaningful additional predictive capacity to identify misclassifications beyond our current smear rules.
不成熟粒细胞百分比（IG%）是感染控制的重要生物标志物。我们观察到一些虚假病例，与手动差异相比，自动化 Sysmex XN 系列血液分析仪大大低估了 IG%。这些病例与“中性粒细胞反应强度”（NEUT-RI）的高值有关，该值应反映中性粒细胞的代谢活性。
我们进行了一项三阶段研究，以评估 NEUT-RI 是否可用于筛选分类错误的 IG%结果，这些结果定义为手动差异估计比自动 Sysmex 差异高 10 个百分点的 IG%。首先，根据 NEUT-RI 值选择 124 例患者样本进行 800 细胞手动涂片分析，并与自动 Sysmex IG%结果进行比较。接下来，将 11098 例常规 110 细胞手动涂片分析与相应的 Sysmex IG%结果进行比较。最后，在 19 天的时间内，根据 NEUT-RI 值≥56 荧光强度（FI）对 160 例额外患者样本进行涂片，以筛选超出我们当前涂片实践的分类错误结果。
NEUT-RI≥56 预测 IG%分类错误的敏感性为 91%，特异性为 88%，但主要是在内部 Sysmex 标志“异常白细胞散射图”存在的情况下。90.1%的分类错误结果由该标志识别。超出我们现有的涂片规则，包括该标志，NEUT-RI≥56 FI 的阳性预测值低于 1%。
NEUT-RI 和内部 Sysmex 标志“异常白细胞散射图”都能很好地识别 IG%分类错误的病例。然而，在我们的环境中，NEUT-RI≥56 FI 除了我们现有的涂片规则之外，对识别分类错误没有有意义的额外预测能力。
