title: Interferon-γ release assay vs. tuberculin skin test for tuberculosis screening in exposed healthcare workers: a longitudinal multicenter comparative study.
abstract: OBJECTIVE
  Healthcare workers (HCWs), especially those caring for patients with tuberculosis (TB), are at high risk of acquiring that disease. The poor specificity of tuberculin skin testing (TST) prompted us to evaluate the effectiveness of the interferon-γ release assay (IGRA) in comparison with TST in a large prospective, multicenter, 1-year study of HCWs with occupational exposure to TB.
  
  
  METHODS
  HCWs from high-risk units at 14 university hospitals were invited to participate and underwent both TST and IGRA (first Quantiferon TB Gold-IT®, QFT-G, then T-SPOT.TB® if QFT-G was indeterminate) at baseline and after 1 year. We collected demographic characteristics, country of birth, history of TB, immunosuppression, past exposure to TB, history of BCG vaccination, results of most recent TST, job category, and duration of current function.
  
  
  RESULTS
  Among 807 HCWs enrolled, current or past TST at baseline was positive (≥15 mm) in 282 (34.9%); the IGRA was positive in 113 (14.0%) and indeterminate in 3 (0.4%). After 1 year, 594 HCWs had both an IGRA and TST (or prior TST≥15 mm) at baseline and an IGRA and TST (if indicated). The conversion rate was 2.5% (9 of 367) with TST and 7.6% (45 of 594) with IGRA, with poor agreement between the 2 tests. Using only QFT-G, conversion (9.9%) and reversion (17.8%) rates were higher for baseline QFT-G positive quantitative values <1 IU/mL.
  
  
  CONCLUSIONS
  TST and the IGRA yielded discordant results. The value of IGRA in addition to TST remains undetermined; the two should be jointly interpreted in decision-making (clinical trial registration NCT00797836).
authors: 1AP-HP,Bichat-Claude Bernard Hospital,Infection Control Unit,F-75018 Paris,France.
authors: Jean-Christophe
authors: JC
authors: Lucet
authors: 3AP-HP,Bichat-Claude Bernard Hospital,Department of Occupational Health,F-75018 Paris,France.
authors: Dominique
authors: D
authors: Abiteboul
authors: 4AP-HP,Bichat-Claude Bernard Hospital,Département d'Epidémiologie et Recherche Clinique,URC Paris-Nord,F-75018 Paris,France.
authors: Candice
authors: C
authors: Estellat
authors: 4AP-HP,Bichat-Claude Bernard Hospital,Département d'Epidémiologie et Recherche Clinique,URC Paris-Nord,F-75018 Paris,France.
authors: Carine
authors: C
authors: Roy
authors: 6AP-HP,Bichat-Claude Bernard Hospital,Unité d'Immunologie "Auto-immunité et Hypersensibilités",F-75018 Paris,France.
authors: Sylvie
authors: S
authors: Chollet-Martin
authors: 4AP-HP,Bichat-Claude Bernard Hospital,Département d'Epidémiologie et Recherche Clinique,URC Paris-Nord,F-75018 Paris,France.
authors: Florence
authors: F
authors: Tubach
authors: 9Univ Paris Diderot,Sorbonne Paris Cité,ECEVE,UMR1123,Paris,F-75010France.
authors: Guislaine
authors: G
authors: Carcelain
mesh_terms: D000328:Adult; D003428:Cross Infection / Q000175:diagnosis* / Q000209:etiology; D006801:Humans; D015994:Incidence; D017758:Infectious Disease Transmission, Patient-to-Professional; D059425:Interferon-gamma Release Tests; D008137:Longitudinal Studies; D008297:Male; D016273:Occupational Exposure; D010564:Personnel, Hospital; D011446:Prospective Studies; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D000069078:Seroconversion; D014374:Tuberculin Test; D014397:Tuberculosis, Pulmonary / Q000175:diagnosis* / Q000209:etiology