The Comparison Of Clinical Value Between T-SPOT.TB And Traditional Approach In Diagnosis Of Active Tuberculosis

BackgroundThe incidence of Tuberculosis (TB) disease in China is prevalent which make China one of the22countries with high TB burden. Recently, the T-SPOT.Ttest, which is based on T-cell response to specific TB antigen, has been carried out among many hospital countrywide. Due to its high specificity and high sensitivity, the diagnostic methodology of TB infection had made a great progress. China is a area with high frequency of tuberculosis latently infection,.However, we are more concerned about the accuracy in diagnosis of active TB in our clinical practice rather than latent TB infection. Therefore, to carry out prospective cohort studys in our country to evaluate the application of these approach is necessary.Methods and Objective144patients with clinically suspected tuberculosis admitted since August2011to May2012from The Third Xiangya Hospital were enrolled in this prospective cohort study.The results (including specificity, sensitivity, accuracy, positive likelihood ratio, negative likelihood ratio, postitive prediction rate and negative prediction rate)of the peripheral blood T-SPOT.TB, TST,TB-Ab were compared with final clinical diagnosis.In order to confirm the ability of T-SPOT.TB to identify active TB or latent infection, the number of spots of the active TB patients and non-active TB patients were statistical analyzed.Result38cases (26.4%) were diagnosed as TB,81cases (56.3%) are to excluded from active tuberculosis.The sensitivity of T-SPOT.TB, TST, TB-Ab for the diagnosis of active TB were92.1%,31.6%、18.4%,and the specificity for the identification of non-active tuberculosis are82.7%、81.0%、83.6%. For the identification of active TB and inactive TB coincidence rate were86.4%,57.5%,57.0%.Three detections for the diagnosis of active TB positive predictive value are71.4%,60.0%,43.8% and negative predictive values are95.7%,56.7%,60.0%, and positive likelihood ratios were5.33,1.66,1.13, and negative likelihood likelihood ratio0.10,0.84,0.98. The CFP-10peptide was non different between active tuberculosis and latent infection group with a median of24.5vs.2spots/2.5105PBMC (P<0.05).ESAT-6was non difference.Conclusion1.T-SPOT.TB has a higher sensitivity for the diagnosis of the active TB, which are significantly better than the TST, TB-Ab. However the positive predictive value of T-SPOT.TB is not high. The final diagnosis should be made with clinical judgement.2.T-SPOT.TB has a lower value of diagnosis for active TB in high TB endemic areas than tuberculosis low-endemic areas, but this study shows a high negative predictive value of the T-SPOT.TB, and a low negative likelihood relatively, suggesting that the T-SPOT.TB negative results help to rule out the diagnosis of tuberculosis.3.There is still no evidence showing that the spot number counting could be used for identification between active TB and latent infection. Since each group has overlapping result.