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: 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 in comparison to Adenosine deaminase (ADA), evaluate the IGRA (T-SPOT.TB) diagnostic efficacy for TPE patients of different characteristics, 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 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 SFCs/10 6 mononuclear cells, 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 40 IU/L, 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.