The Diagnostic Value Of The Detection Of Mycobacterium Tuberculosis T Cells (T-SPOT.TB) In Active Tuberculosis

Background and ObjectiveWHO global TB report in 2015 suggested that global TB incidence has fallen by 18% since 2000,an average annual decline of about 1.5%.The death rate has fallen by 47% since 1990.Despite great achievements,tuberculosis remains the world's most serious public health threat.In 2014 worldwide death toll of TB was 1 million 500 thousand,nearly 960 million new cases in china.China is one of the countries with the highest incidence of tuberculosis in the world,ranked second only to India.It is difficult to diagnose and treat for a long time,which seriously affects people's daily life.Before the diagnosis of tuberculosis often rely on the PPD test,but it has many limitations,in recent years,new diagnostic means--the Detection of Mycobacterium Tuberculosis T cells(T-SPOT.TB),a new method for the diagnosis of MTB infection,the purpose of this study is to investigate the diagnostic value of T-SPOT.TB of active tuberculosis,and analyzed the risk factors for false negative and false positive effects of T-SPOT.TB.MethodsWe retrospectively screened active TB suspects that re hospitalized in the Respiratory department of Henan Province People's Hospital,during June 2015 and October 2015,totally 450.General information and past history are collected.According to their final diagnosis,the patients were divided into active TB group,previous TB group and non-TB group.We evaluated the diagnostic value of T-SPOT.TB assay by drawing the ROC curve and calculating the optimal diagnostic boundary value.In addition,the difference of A antigen and B antigen in T-SPOT.TB in each group was compared.ResultThe sensitivity,specificity,positive predictive value,negative predictive value,the positive likelihood ratio and the negative likelihood ratio of T-SPOT.TB in active tuberculosis was 89.78%,63.16%,0.56,0.92,2.47,and 0.16,respectively.In terms of the ROC curve in active tuberculosis,the area under the curve of the A antigen(0.89)was higher than that of the B antigen(0.86),and when A antigen was 13.5 SFCs/2.5*105PBMC,the diagnosis value is optimal.The area under the curve of A antigen and B antigen was 0.60 and 0.58 in old tuberculosis,and the diagnostic value of T-SPOT.TB was poor.The value of A and B antigens in active TB group had a statistically significant difference from non tuberculosis group and old pulmonary tuberculosis group(A antigen ?2=105.41,P < 0.01,B antigen ?2=91.03,P < 0.01;A antigen ?2=12.99,P < 0.01,B antigen ?2=8.56,P <0.01).In the non tuberculosis group and old pulmonary tuberculosis group,there was no statistical difference(A antigen ?2=1.07,P>0.05,B antigen ?2=0.77,P>0.05).The history of BCG vaccination on the occurrence of false positive was no statistically significant(P < 0.05);these factors,such as 65 years of age or older,decreased immunity,body mass index(BMI)< 16kg/m2,are related to the occurrence of false negative in statistical significance(P < 0.05).ConclusionT-SPOT.TB has high sensitivity and specificity in the diagnosis of active tuberculosis,which can provide an important reference value for the diagnosis of active tuberculosis,it cannot be affected by previous tuberculosis and BCG vaccination.