The Study Of The Diagnostic Value Of T-SPOT.TB And TB-Ab And Their Combined Detection In Tuberculosis

Object:To investigate the diagnostic value of tuberculous infection of T cell spot test(T-SPOT.TB)and anti-tuberculosis antibody(TB-Ab)assay and their combined detection in tuberculosis.Methods:Clinical data of 257 patients with suspected tuberculosis who were hospitalized in shangrao people's Hospital from July 2016 to July 2017 were retrospectively collected.According to the latest diagnostic criteria,142 tuberculosis patients and 115non-tuberculosis patients were finally confirmed.T-SPOT.TB and TB-Ab tests were detected on all suspected patients,by means of which the validity index,reliability index and performance index of the diagnostic tests reflect the diagnostic value of the two experiments in single use and in combination use.SPSS22.0 was used for data analysis.Result:(1)The positive rate of T-SPOT.TB and TB-Ab were 88.7% and 60.6%respectively in tuberculosis patients,higher than those in non-tuberculosis patients(20.9%,23.5%),which showed statistically significant difference(P<0.001).(2)The sensitivity(88.7%,95% CI:83.5%~94.0%),specificity(79.1%,95%CI:71.6%~86.7%),positive predictive value(PPV)(84.0%,95%CI:78.1%~89.9%),negative predictive value(NPV)(85.0%,95%CI:78.2%~91.9%),positive likelihood ratio(PLR)(4.252,95%CI:2.964~6.098),consistency(84.4%,95%CI:79.9%~88.9%)and the area under the receiver operating characteristic curve,(AUC)(0.839,95%CI:0.786 ~ 0.892)in T-SPOT.TB were higher than those in TB-Ab test(the sensitivity(60.6%,95%CI:52.4%~68.7%),specificity(76.5,95% CI:68.7%~84.4%),PPV(76.1%,95%CI:68.1%~84.1%),NPV(61.1%,95%CI:53.1%~69.2%),PLR(2.580,95%CI:1.808~3.681),consistency(67.7%,95%CI:61.9%~73.5%),and AUC(0.685,95%CI:0.620~0.751)).which showed statistically significant differences in sensitivity,negative predictive value,consistency and the area under ROC curve(P<0.05).The negative likelihood ratio of T-SPOT.TB assay was 0.143(95%CI:0.089~0.228),lower than that of TB-Ab 0.515((95%CI:0.410~0.647),and the difference was statistically significant(P<0.05).(3)The sensitivity of parallel combination of T-SPOT.TB and TB-Ab test was95.8%(95%CI:92.4%~99.12%),higher than that in single use of T-SPOT.TB and TB-Ab(P<0.05).The specificity of series combination of T-SPOT.TB and TB-Ab test was 93.9%(95%CI:89.5%~98.4%),higher than that in single use of T-SPOT.TB and TB-Ab(P<0.05).(4)The area under ROC curve(AUC)of the two methods based on Logistic regression was higher than that of the AUC of parallel and series,and had no overlap with the 95% confidence interval of series,compared with that of parallel and series,which showed statistically significant difference.Conclusion:(1)The sensitivity,negative predictive value,consistency,the area under ROC curve and negative likelihood ratio of T-SPOT.TB are superior to those of TB-Ab test.(2)The combined detection of T-SPOT.TB and TB-Ab showed that parallel test greatly increased the sensitivity while series test greatly improved the specificity of the diagnosis in tuberculosis.The choice of the combined approaches can be based on practical need.