应用ROC曲线确定流式细胞术髓过氧化酶检测结果在急性白血病分类中的最佳临界值

Detecting Optimal Cut-off Value of Flow Cytometry Myeloperoxidase（fMPO） by Receiver Operator Characteristic Curve in the Classification of Acute Leukemia

目的 用受试者工作曲线（ROC曲线）法,评价流式细胞术髓过氧化酶检测（fMPO）在急性白血病分类中的预测和诊断价值,并确定其在急性白血病分类中的最佳临界值（Cut-off）.方法 收集武汉大学人民医院2010年1月～2012年6月血液科门诊及住院急性白血病（ALS）患者198例,其中急性髓性白血病（AML）119例,急性淋巴细胞白血病（ALL） 54例和急性未分类白血病25例.采用流式细胞术（FCM）和酶细胞化学技术对MPO进行测定,以细胞化学法MPO（CMPO）≥3％和/或≥两种泛髓细胞标准物表达作为鉴别诊断急性髓细胞白血病的金标准.并用SSPS软件绘制ROC曲线确定最佳临界值,并将其与fMPO临界值为3％和10％时的诊断效能指标（敏感度、特异度、误诊率、漏诊率、阳性预告值、阴性预告值）进行初步对比.结果 AML组和急性未分类白血病组fMPO水平显著高于ALL组（U=40,41;P均＜0.05）.ROC曲线显示曲线下面积（AUC）为0.967,标准误0.04,95％置信区间为0.85～1.0,依据Youden指数最大原则,确定fMPO最佳临界值为5.5％ ,此时灵敏度为98.7％,特异度为92.1％,其特异度明显高于fMPO为3％时的22.2％和10％时的70％（χ2=11.23,8.11;P均＜0.05）,而灵敏度3％时的98.6％和10％时的96.5％差异无统计学意义（χ2=0.72,0.61;P均＞0.05）.结论 fMPO临界值5.5％作为急性白血病分类的诊断界值比较合适,可以提高临床的诊断.

Objective To evaluate the value of flow cytometry myeloperoxidase （fMPO） in the classification of acute leukemia and determine the optimal cut-off value of fMPO for the classification of acute leukemia by receiver operator characteristic （ROC） curve. Methods By retrospective analysis,with acute leukemia （ALS） 198 cases,119 cases of acute myeloid leuke- mia （AML） （AML group）, 54 cases of acute lymphoblastic leukemia （ALL group） and 25 cases of acute leukemia unclassi- fied, by flow cytometry （FCM） and enzyme cytochemical techniques,MPO was determined by cell chemistry MPO （CMPO） ≥3% and/or≥two pan-myeloid expression gold standard as a differential diagnosis of acute myeloid leukemia standards. And draw the ROC curve to determine the optimal threshold value,and with 3% and 10% of fMPO cut-off value in the dif- ferential diagnosis of AML,sueh as a preliminary comparison of the effectiveness of using SSPS software. Reasults FMPO AML group was significantly higher than ALL group, acute leukemia Unclassified group and control group. ROC curve showed the area under the curve （AUC） was 0. 967,standard error of 0.04,95 % confidence interval 0.85 to 1.0,based on the principle of maximum Youden index to determine the optimal cut-off value of 5.5 % fMPO, when sensitivity was 98.7 %, the specificity was 92.1% ,significantly higher than 98.6% and 22.2% of fMPO 3% and 96.5% and 70% of fMPO 10%. Conclusion fMPO cut-off value of 5.5 % as a diagnostic cutoff value moreappropriate classification of acute leukemia, can improve clinical diagnosis.