title: Role of QuantiFERON(®)-TB Gold In-Tube in tuberculosis contact investigation: experience in a tuberculosis unit.
abstract: BACKGROUND
  Interferon-γ release assays (IGRAs) are increasingly used for the diagnosis of latent tuberculosis infection (LTBI). Because of the lack of a gold standard for the diagnosis of LTBI, IGRAs are compared to the tuberculin skin test (TST) and yield conflicting results. We assessed the usefulness of an IGRA test, QuantiFERON(®)-TB Gold In-Tube (QFT-G-IT), for diagnosing LTBI compared with TST in the setting of a contact screening study.
  
  
  METHODS
  A prospective comparison between the QFT-G-IT and the TST in TB contact subjects in a low TB burden area was conducted sequentially between January 2006 and December 2012.
  
  
  RESULTS
  A moderate concordance between the two tests (κ = 0.44 for TST cut-off of 5 mm and κ = 0.56 for TST cut-off of 15 mm) was found. A better agreement was shown in younger contacts and in non-vaccinated contacts when using a TST of 15 mm. Independent risk factors for a TST(+)/QFT-G-IT(-) discordance were history of BCG vaccination and age between 31 and 59 years. Discordance was also more frequent using a TST cut-off value of 5 mm. QFT-G-IT(+)/TST(-) was infrequent and was found in older contacts.
  
  
  CONCLUSIONS
  Based on our data, we cannot recommend the use of QFT-G-IT as the only test to rule out LTBI, especially in older patients.
authors.affiliation: Department of Internal Medicine - Infectious Diseases, Hospital Son Llàtzer , Palma de Mallorca , Spain.
authors.forename: Juan
authors.initials: J
authors.lastname: Gonzślez-Moreno
authors.forename: Mercedes
authors.initials: M
authors.lastname: García-Gasalla
authors.forename: Cristina
authors.initials: C
authors.lastname: Gállego-Lezaun
authors.forename: Victoria
authors.initials: V
authors.lastname: Fernández-Baca
authors.forename: Isabel
authors.initials: I
authors.lastname: Mir Viladrich
authors.forename: Carmen
authors.initials: C
authors.lastname: Cifuentes-Luna
authors.forename: Araceli
authors.initials: A
authors.lastname: Serrano Bujalance
authors.forename: Andrea
authors.initials: A
authors.lastname: Salom Vallespir
authors.forename: Antoni
authors.initials: A
authors.lastname: Payeras Cifre
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000995:Antitubercular Agents / Q000627:therapeutic use; D002648:Child; D002675:Child, Preschool; D016358:Contact Tracing; D005260:Female; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D059425:Interferon-gamma Release Tests / Q000379:methods* / Q000592:standards*; D055985:Latent Tuberculosis / Q000175:diagnosis* / Q000188:drug therapy / Q000453:epidemiology*; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies; D015203:Reproducibility of Results; D014374:Tuberculin Test; D055815:Young Adult
chemical_list: D000995:Antitubercular Agents
keywords: IGRA; QuantiFERON-TB -Gold In-Tube; tuberculosis