Hantaweepant Chattree, Sasijareonrat Natthaporn, Chutvanichkul Boonyanuch, Karaketklang Khemajira, Chinthammitr Yingyong
Division of Haematology, Department of Medicine, Faculty of Medicine Siriraj Hospital Mahidol University Bangkok Thailand.
Department of Medicine, Faculty of Medicine Siriraj Hospital Mahidol University Bangkok Thailand.
Health Sci Rep. 2019 Nov 29;3(1):e138. doi: 10.1002/hsr2.138. eCollection 2020 Mar.
Diagnosis of thrombotic microangiopathy (TMA) relies on microscopic schistocyte determination by an experienced microscopist. In addition, schistocytes can be found in non-TMA-related disorders such as thalassaemia. We aimed to compare the accuracy of the automated haematology analyser Sysmex XN-3000 for schistocyte detection, to that of the microscopy approach, in patients suspected of having schistocytosis.
Consecutive blood samples were collected between April 2016 and March 2017 at Siriraj Hospital, Mahidol University, Bangkok, Thailand. Specimens were collected from adults with suspected TMA or with thalassaemia trait and/or disease. All blood samples were examined by both microscopy and the analyser. Samples were considered to be positive for schistocytes (ie, schistocytosis) if they had a schistocyte count ≥1% by microscopy. The analyser's ability to determine schistocytosis was assessed by receiver operating characteristic (ROC) curve. Sensitivity, specificity, positive (PPV), and negative predictive value (NPV) of an appropriate cut-off point were calculated, with manual microscopy as the standard. Quantitative agreement in schistocyte counts between the two approaches was assessed using 95% limits of agreement, Bland-Altman plots, intraclass correlation coefficient, and concordance correlation coefficient.
Ninety-seven blood samples (62 suspected TMA and 35 thalassaemia) were collected. ROC curve analysis of the analyser for determining schistocytosis showed an area under the curve of 0.803 (95% confidence interval, 0.689-0.917, < 0.001). A cut-off point of 0.6% yielded 86.1% sensitivity, 77.8% specificity, 94.4% PPV, and 56.0% NPV. The automated schistocyte count did not quantitatively agree with schistocyte counts by microscopy, neither in all blood specimens (mean of difference: -1.09; 95% limits of agreement, -11.9 to 9.7) nor in the subgroups (TMA, -0.88; 95% limits of agreement, -6.60 to 4.84; thalassaemia, -2.4; 95% limits of agreement, -14.10 to 9.30). The differences in the estimation of fragmented red blood cells between the methods tended to increase at higher schistocyte counts.
Sysmex XN-3000 can be used for qualitative measurement of schistocytosis, but should not be used as a quantitative tool for schistocyte counting. Improvements are needed before this analyser's schistocyte detection feature can be recommended for use in clinical practice.
血栓性微血管病（TMA）的诊断依赖于经验丰富的显微镜检查人员通过显微镜观察来确定裂红细胞。此外，在诸如地中海贫血等非TMA相关疾病中也可发现裂红细胞。我们旨在比较全自动血液分析仪Sysmex XN - 3000与显微镜检查方法在疑似存在裂红细胞增多症患者中检测裂红细胞的准确性。
2016年4月至2017年3月期间，在泰国曼谷玛希隆大学诗里拉吉医院连续采集血样。样本采自疑似患有TMA或具有地中海贫血特征和/或疾病的成年人。所有血样均通过显微镜检查和分析仪进行检测。如果通过显微镜检查裂红细胞计数≥1%，则样本被认为裂红细胞呈阳性（即裂红细胞增多症）。通过受试者操作特征（ROC）曲线评估分析仪检测裂红细胞增多症的能力。计算以手工显微镜检查为标准的适当截断点的灵敏度、特异性、阳性预测值（PPV）和阴性预测值（NPV）。使用95%一致性界限、Bland - Altman图、组内相关系数和一致性相关系数评估两种方法在裂红细胞计数方面的定量一致性。
共采集了97份血样（62份疑似TMA和35份地中海贫血）。分析仪检测裂红细胞增多症的ROC曲线分析显示曲线下面积为0.803（95%置信区间，0.689 - 0.917，P < 0.001）。截断点为0.6%时，灵敏度为86.1%，特异性为77.8%，PPV为94.4%，NPV为56.0%。自动裂红细胞计数与显微镜检查的裂红细胞计数在所有血标本中（差异均值： - 1.09；95%一致性界限， - 11.9至9.7）以及各亚组中（TMA， - 0.88；95%一致性界限， - 6.60至4.84；地中海贫血， - 2.4；95%一致性界限， - 14.10至9.30）在数量上均不一致。两种方法在估计破碎红细胞数量上的差异在裂红细胞计数较高时趋于增大。
Sysmex XN - 3000可用于裂红细胞增多症的定性检测，但不应作为裂红细胞计数的定量工具。在推荐该分析仪的裂红细胞检测功能用于临床实践之前，还需要改进。
