title: Comparison of interferon-gamma release assay versus tuberculin skin test for tuberculosis screening in inflammatory bowel disease.
abstract: OBJECTIVE
  Reactivation of latent tuberculosis (TB) in inflammatory bowel disease (IBD) patients treated with antitumor necrosis factor-alpha medication is a serious problem. Currently, TB screening includes chest x-rays and a tuberculin skin test (TST). The interferon-gamma release assay (IGRA) QuantiFERON-TB Gold In-Tube (QFT-G-IT) shows better specificity for diagnosing TB than the skin test. This study evaluates the two test methods among IBD patients.
  
  
  METHODS
  Both TST and IGRA were performed on 212 subjects (114 Crohn's disease, 44 ulcerative colitis, 10 indeterminate colitis, 44 controls).
  
  
  RESULTS
  Eighty-one percent of IBD patients were under immunosuppressive therapy; 71% of all subjects were vaccinated with Bacille Calmette Guérin; 18% of IBD patients and 43% of controls tested positive with the skin test (P < 0.0001). Vaccinated controls tested positive more often with the skin test (52%) than did vaccinated IBD patients (23%) (P = 0.011). Significantly fewer immunosuppressed patients tested positive with the skin test than did patients not receiving therapy (P = 0.007); 8% of patients tested positive with the QFT-G-IT test (14/168) compared to 9% (4/44) of controls. Test agreement was significantly higher in the controls (P = 0.044) compared to the IBD group.
  
  
  CONCLUSIONS
  Agreement between the two test methods is poor in IBD patients. In contrast to the QFT-G-IT test, the TST is negatively influenced by immunosuppressive medication and vaccination status, and should thus be replaced by the IGRA for TB screening in immunosuppressed patients having IBD.
authors.affiliation: Department of Gastroenterology, Inselspital, University of Bern, Switzerland.
authors.forename: Alain M
authors.initials: AM
authors.lastname: Schoepfer
authors.forename: Beatrice
authors.initials: B
authors.lastname: Flogerzi
authors.forename: Silvia
authors.initials: S
authors.lastname: Fallegger
authors.forename: Thomas
authors.initials: T
authors.lastname: Schaffer
authors.forename: Stefan
authors.initials: S
authors.lastname: Mueller
authors.forename: Laurent
authors.initials: L
authors.lastname: Nicod
authors.forename: Frank
authors.initials: F
authors.lastname: Seibold
mesh_terms: D000998:Antiviral Agents; D006801:Humans; D015212:Inflammatory Bowel Diseases / Q000150:complications*; D007371:Interferon-gamma; D008403:Mass Screening; D011933:Reagent Kits, Diagnostic; D014374:Tuberculin Test; D014376:Tuberculosis / Q000150:complications / Q000175:diagnosis*
chemical_list: D000998:Antiviral Agents; D011933:Reagent Kits, Diagnostic; D007371:Interferon-gamma