Xpert MTB/RIF检测技术对肺结核的诊断价值

Diagnostic value of Xpert MTB/RIF assay in pulmonary tuberculosis

目的探讨Xpert MTB/RIF检测技术在肺结核中的诊断价值。方法选取2017年9月至2019年7月于武汉大学中南医院住院疑似肺结核的765例患者为研究对象。本研究共收集到428份痰液、263份肺泡灌洗液及74份胸水,分别进行涂片抗酸染色和Xpert MTB/RIF检测,同时采集到237例患者的静脉血,用于进行γ-干扰素释放试验(IGRA)。以临床最终诊断结果为金标准评估和比较各种检测方法对肺结核的诊断价值。结果 765例疑似肺结核患者中,195例被确诊为肺结核,570例为非肺结核,Xpert MTB/RIF检测对肺结核的诊断灵敏度为54.87%,特异度为99.12%,阳性预测值为95.54%,阴性预测值为86.52%,准确度为87.84%,阳性检出率为14.64%,同时可测得利福平耐药性检出率为6.25%;涂片抗酸染色镜检诊断肺结核的灵敏度为12.31%,特异度和阳性预测值均为100.00%,阴性预测值为76.92%,准确度为77.65%,阳性检出率为3.14%;χ2检验结果显示,Xpert MTB/RIF诊断肺结核的阳性检出率、灵敏度及准确度均明显高于涂片镜检,差异均有统计学意义(P<0.05);Kappa检验结果表明,Xpert MTB/RIF检测与临床诊断结果的一致性优于涂片镜检,K值分别为0.628和0.173;Xpert MTB/RIF与γ-干扰素释放试验联合检测可提高诊断灵敏度和诊断准确度;Xpert MTB/RIF检测对不同类型标本检测效能不同,肺泡灌洗液是最佳选择;χ2检验表明,三组不同类型的标本阳性检出率、灵敏度、阴性预测值及准确度比较差异有统计学意义(P<0.05),其中痰组与肺泡灌洗液组阳性检出率、灵敏度、阴性预测值及准确度比较差异无统计学意义(P>0.05),但均明显高于胸水组,差异有统计学意义(P<0.05);痰组、肺泡灌洗液组与临床诊断结果一致性较好,远高于胸水组(K值分别为0.624、0.728和0.252)。结论与涂片抗酸染色镜检等传统方法相比,Xpert MTB/RIF检测技术具有高灵敏度,高特异度等优点,并且能同时判断结核杆菌利福平耐药性,在肺结核中诊断价值较高,可为临床诊疗方案的选择提供有效参考。

Objective To evaluate the diagnostic value of Xpert MTB/RIF assay in pulmonary tuberculosis.Methods A total of 765 inpatients with suspected pulmonary tuberculosis(PTB) in Zhongnan Hospital of Wuhan University from September 2017 to July 2019 were enrolled in this study. A total of 428 sputum samples, 263 broncho alveolar lavage fluids(BALF), and 74 pleural fluids were collected for smear microscopy(SM) and Xpert MTB/RIF assay, respectively. Besides, 237 blood samples were also collected for γ-interferon gamma release assay(IGRA). The final clinical diagnosis results were taken as the gold standard to assess the diagnostic value of various detection methods for pulmonary tuberculosis. Results Of the 765 inpatients with suspected PTB, 195 were diagnosed as pulmonary tuberculosis and 570 as non-pulmonary tuberculosis. Compared to the final diagnosis, the sensitivity, specificity, positive predictive value(PPV), negative predictive value(NPV), accuracy, and positive detection rate of Xpert MTB/RIF were54.87%, 99.12%, 95.54%, 86.52%, 87.84%, and 14.64%, respectively. The detection rate of rifampicin resistance was6.25%. The sensitivity, specificity, PPV, NPV, accuracy, and positive detection rate of smear microscopy were 12.31%,100.00%, 100.00%, 76.92%, 77.65%, and 3.14%, respectively. The results of Chi-square test showed that the positive detection rate, sensitivity, and accuracy of Xpert MTB/RIF were significantly higher than those of SM(P<0.05). The results of Kappa test showed that the consistency between Xpert MTB/RIF and clinical diagnosis was better than that of SM, and the K values were 0.628 and 0.173, respectively. Combined detection of Xpert MTB/RIF and IFN-γ release test can improve the diagnostic sensitivity and accuracy. The detection efficiency of Xpert MTB/RIF was different for different types of specimens, and BALF was the best choice. χ2 test showed that there were significant differences in the positive detection rate, sensitivity, negative predictive value, and accuracy between types of specimens(P<0.05). The positive detection rate, sensitivity, negative predictive value, and accuracy showed no statistically significant difference between the sputum group and the BALF group(P>0.05), but they were significantly higher than those of the pleural fluids group(P<0.05). The consistency between the sputum group and the BALF group was better than that of the pleural fluids group(K values were 0.624, 0.728 and 0.252, respectively). Conclusion Compared with the traditional methods,Xpert MTB/RIF assay has the advantages of high sensitivity and high specificity. It can also make a rapid judgment of rifampicin resistance at the same time, which provides an effective reference for clinical diagnoses and treatment for drug-resistant tuberculosis.