title: An interferon-gamma release assay test performs well in routine screening for tuberculosis.
abstract: BACKGROUND
  A positive interferon-gamma release assay (IGRA) is regarded as proof of latent Mycobacterium tuberculosis infection. We conducted an evaluation of the IGRA test "T-SPOT.TB" to test its performance during clinical routine use by analysing the positivity rate and odds, effect of season and sensitivity.
  
  
  METHODS
  Data from T-SPOT.TB testing together with age and test indications (anti-tumour necrosis factor alpha (TNFα) candidate, contact investigation or suspicion of tuberculosis (TB)) were combined with mycobacteria culture results.
  
  
  RESULTS
  A total of 1,809 patients were tested. Conclusive results were achieved for 1,780 patients (98.4%). Among these, 4.6% of anti-TNFα candidates, 19.3% of contacts and 24.4% of TB suspects tested positive. Compared with anti-TNFα candidates, the odds for a positive result were significantly higher for contact investigations (odds ratio (OR), mean (95% confidence interval): 4.93 (3.11-7.81)) and TB suspects (OR: 6.83 (4.33-10.77)). Elevated odds of an inconclusive test were found during autumn and winter periods (OR: 2.53 (1.58-4.05)) and for patients > 75 years of age (OR: 2.66 (1.43-4.94)) and < 6 years of age (OR: 3.35 (1.58-7.09)). In all, 41 of 43 culture-verified M. tuberculosis infections tested positive with one false negative.
  
  
  CONCLUSIONS
  During routine testing, inconclusive tests were rare, but more frequent during autumn/winter periods and for patients < 6 and > 75 years of age. The T-SPOT.TB showed a high sensitivity in culture-verified TB, although false negative results did occur.
  
  
  BACKGROUND
  not relevant.
  
  
  BACKGROUND
  not relevant.
authors.affiliation: Lungemedicinsk Afdeling, Aarhus Universitetshospital, Nørrebrogade 44, 8000 Aarhus, Denmark. alladani@rm.dk.
authors.forename: Allan Vestergaard
authors.initials: AV
authors.lastname: Danielsen
authors.forename: Andreas
authors.initials: A
authors.lastname: Fløe
authors.forename: Troels
authors.initials: T
authors.lastname: Lillebaek
authors.forename: Hans Jürgen
authors.initials: HJ
authors.lastname: Hoffmann
authors.forename: Ole
authors.initials: O
authors.lastname: Hilberg
mesh_terms: D000293:Adolescent; D000328:Adult; D000367:Age Factors; D000368:Aged; D002648:Child; D016358:Contact Tracing; D005188:False Negative Reactions; D006801:Humans; D059425:Interferon-gamma Release Tests; D055985:Latent Tuberculosis / Q000175:diagnosis* / Q000188:drug therapy / Q000635:transmission; D008403:Mass Screening / Q000379:methods*; D008875:Middle Aged; D016017:Odds Ratio; D012621:Seasons; D012680:Sensitivity and Specificity; D014409:Tumor Necrosis Factor-alpha / Q000037:antagonists & inhibitors; D055815:Young Adult
chemical_list: D014409:Tumor Necrosis Factor-alpha