The utility of T-SPOT.TB for the diagnosis unconventional pleural tuberculosis is superior to ADA in high prevalence: A perspective analysis of 601 cases

Abstract BACKGROUND Recently, Interferon Gamma Release Assay (IGRA) is still controversial in differentiating tuberculous pleural effusion (TPE), through recommended by World Health Organization (WHO )for identification of latent tuberculosis infection. OBJECTIVES Aim to qualify the diagnostic efficacy for TPE by IGRA in comparison to Adenosine deaminase(ADA), to clarify its appropriate scene in clinical diagnosis. METHODS A prospective, single-centre study including all suspected pleural effusion patients consecutively from June 2015 to October 2018. Through receiver operating characteristic (ROC) curves, all enrolled participants were determined technical cut-off and the utility of IGRA(T-SPOT)for pleural fluid(PF). Obtain the independent risk factors by logistic regression analysis for TPE, and evaluate the performance of T-SPOT stratified by risk factors, in comparison to ADA. RESULTS A total of 601 individuals were consecutively recruited. The maximum of early secretory antigenic target-6 (ESAT-6) and culture filtrate protein-10 (CFP-10) in PF T-SPOT had the best diagnostic efficiency in our study, with a sensitivity of 83.0% and a specificity of 83.1%, corresponding cut-off value is 466, which was equal to ADA(0.885 vs 0.887, P=0.957) and superior than in PB; Among the TPE patients with low ADA(<40 IU/L), the sensitivity and specificity of PF T-SPOT was still 87.9%, 90.5% respectively. The utility of ADA was negative related to age ascents, but PF T-SPOT had steady performance at any age-stage. The age (<45 yrs; odds ratio (OR) 5.61), gender (male; OR 2.7) and body mass index (BMI)(<22; OR 1.93) was independently associated with the risk of TB by multivariate logistic regression analysis. Stratified by risk factors, notably the PF T-SPOT had superior sensitivity(76.5% vs. 23.5%,P=0.016) than ADA meanwhile had the non-inferior specificity(84.4% vs. 96.9%, P=0.370). CONCLUSIONS In conclusion, the overall potency of PF T-SPOT assay is equal to ADA for diagnosing TPE. In addition, PF T-SPOT can effectively discriminate the TPE patients whose ADA lower than 40IU/L, and extremely superior to ADA in unconventional TPE patients(age>45yrs, female or BMI<22). PF T-SPOT assay is an extremely good choice to supplement ADA to diagnose TPE.