Xuan Wei-Xia, Lu Ting-Ting, Wang Zheng, An Yun-Xia, Zhang Xiao-Ju
Department of Respiratory and Critical Medicine, The People's Hospital of Zhengzhou University, Zhengzhou, Henan 450003, China.
Chin Med J (Engl). 2017 Apr 5;130(7):811-816. doi: 10.4103/0366-6999.202738.
Active tuberculosis (TB) with negative results of sputum smear is difficult to be identified. Till now, there is no effective and noninvasive diagnostic method. This study evaluated the diagnostic power of Mycobacterium tuberculosis T-cell (T.SPOT®.TB) assays for active TB.
We retrospectively screened 450 suspected TB patients that were hospitalized in the Respiratory Department of Henan Province People's Hospital from June 2015 to June 2016. The patients were divided into the active, previous, and non-TB groups according to their final diagnosis. We evaluated the diagnostic value of the T-SPOT®.TB assay by constructing receiver operating characteristic (ROC) curves and calculating the optimal diagnostic cutoff value. In addition, we compared the levels of A antigen (ESAT-6) and B antigen (CFP-10) in active TB.
The sensitivity, specificity, positive predictive value, negative predictive value, positive likelihood ratio, and negative likelihood ratio of T-SPOT®.TB for active TB were 89.78%, 63.16%, 0.56, 0.92, 2.47, and 0.16, respectively. For active TB, the area under the ROC curve (AUC) of the A antigen (0.89) was higher than that of the B antigen (0.86). The AUC of the A antigen for active TB was largest at a cutoff value of 13.5 spot-forming cells (SFCs) per 2.5 × 105 peripheral blood mononuclear cells (PBMCs). The AUC of the A and B antigens was 0.60 and 0.58 for previous TB. The levels of A and B antigen in the active TB group were significantly different from those in the previous- and non-TB groups (A antigen: χ2 = 105.41, P< 0.01 and B antigen: χ2 = 91.03, P< 0.01; A antigen: χ2 = 12.99, P< 0.01 and B antigen: χ2 = 8.56, P< 0.01, respectively). There were no significant differences in the levels of A and B antigens between the non-TB group and previous TB group (A antigen: χ2 = 1.07, P> 0.05 and B antigen: χ2 = 0.77, P> 0.05).
T-SPOT®.TB has high sensitivity and specificity for the diagnosis of active TB at a cutoff value of 13.5 SFCs per 2.5 × 105 PBMCs and is not influenced by previous TB.
痰涂片结果为阴性的活动性肺结核难以确诊。目前，尚无有效的非侵入性诊断方法。本研究评估了结核分枝杆菌T细胞（T.SPOT®.TB）检测对活动性肺结核的诊断效能。
我们回顾性筛选了2015年6月至2016年6月在河南省人民医院呼吸内科住院的450例疑似肺结核患者。根据最终诊断将患者分为活动性肺结核组、陈旧性肺结核组和非肺结核组。通过构建受试者工作特征（ROC）曲线并计算最佳诊断临界值，评估T-SPOT®.TB检测的诊断价值。此外，我们比较了活动性肺结核患者中A抗原（ESAT-6）和B抗原（CFP-10）的水平。
T-SPOT®.TB检测对活动性肺结核的敏感性、特异性、阳性预测值、阴性预测值、阳性似然比和阴性似然比分别为89.78%、63.16%、0.56、0.92、2.47和0.16。对于活动性肺结核，A抗原的ROC曲线下面积（AUC）（0.89）高于B抗原（0.86）。当每2.5×105外周血单个核细胞（PBMC）中斑点形成细胞（SFC）的临界值为13.5时，A抗原对活动性肺结核的AUC最大。对于陈旧性肺结核，A抗原和B抗原的AUC分别为0.60和0.58。活动性肺结核组中A抗原和B抗原的水平与陈旧性肺结核组和非肺结核组有显著差异（A抗原：χ2 = 105.41，P<0.01；B抗原：χ2 = 91.03，P<0.01；A抗原：χ2 = 12.99，P<0.01；B抗原：χ2 = 8.56，P<0.01）。非肺结核组和陈旧性肺结核组之间A抗原和B抗原的水平无显著差异（A抗原：χ2 = 1.07，P>0.05；B抗原：χ2 = 0.77，P>0.05）。
当每2.5×105 PBMC中SFC的临界值为13.5时，T-SPOT®.TB对活动性肺结核的诊断具有高敏感性和特异性，且不受陈旧性肺结核的影响。
