title: Adapted T cell interferon-gamma release assay for the diagnosis of pleural tuberculosis.
abstract: BACKGROUND
  Better and more rapid tests are needed for the diagnosis of tuberculous pleural effusion (TPE), given the known limitations of conventional diagnostic tests.
  
  
  OBJECTIVE
  To estimate diagnostic accuracy of the QuantiFERON-TB Gold In-Tube (QFT-GIT) test (and its components) using data-derived cutoffs in pleural fluid.
  
  
  METHODS
  The QFT-GIT test was performed on whole blood and pleural fluid from 43 patients with TPE and 29 control subjects (non-TPE). To achieve the objective, QFT-GIT test, estimating likelihood ratios and receiver operating curve analysis were performed.
  
  
  RESULTS
  The sensitivity and specificity using the QFT-GIT for the diagnosis of TPE were 48.8% and 79.3%, respectively, in pleural fluid. The best cutoff points for tuberculosis (TB) antigen, nil and TB antigen minus nil results were estimated at 0.70, 0.90 and 0.30 IU/ml, respectively. Area under the curve of TB antigen IFN-γ response was 0.86 (CI: 0.76-0.93), nil tube was 0.80 (CI: 0.69-0.89) and TB antigen minus nil tube was 0.82 (CI: 0.72-0.90). When the best cutoff scores of the nil tubes were set at this value, the results of a likelihood ratio of a positive and a negative test were 9.44 (7.4-12.0) and 0.37 (0.09-1.5), respectively. The percentages of indeterminate results in pleural fluid among the TPE cases were 42% (most of them caused by high nil IFN-γ values) using the QFT-GIT test.
  
  
  CONCLUSIONS
  QFT-GIT test or its components have poor accuracy in the diagnosis of TPE, largely because of a high number of indeterminate results due to high background IFN-γ production in the TPE.
authors.affiliation: Department of Chest Diseases, Faculty of Medicine, University of Dicle, Diyarbakir, Turkey. gungorates@yahoo.com
authors.forename: Gungor
authors.initials: G
authors.lastname: Ates
authors.forename: Tekin
authors.initials: T
authors.lastname: Yildiz
authors.forename: Mediha Gonenc
authors.initials: MG
authors.lastname: Ortakoylu
authors.forename: Tuncer
authors.initials: T
authors.lastname: Ozekinci
authors.forename: Baykal
authors.initials: B
authors.lastname: Erturk
authors.forename: Levent
authors.initials: L
authors.lastname: Akyildiz
authors.forename: Emel
authors.initials: E
authors.lastname: Caglar
mesh_terms: D000328:Adult; D000465:Algorithms; D019540:Area Under Curve; D015415:Biomarkers; D005260:Female; D006801:Humans; D007371:Interferon-gamma / Q000097:blood*; D059425:Interferon-gamma Release Tests; D008297:Male; D009169:Mycobacterium tuberculosis / Q000472:pathogenicity*; D016017:Odds Ratio; D011933:Reagent Kits, Diagnostic; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D013601:T-Lymphocytes / Q000276:immunology*; D014396:Tuberculosis, Pleural / Q000175:diagnosis* / Q000276:immunology
chemical_list: D015415:Biomarkers; D011933:Reagent Kits, Diagnostic; D007371:Interferon-gamma