title: Factors impacting the results of interferon-γ release assay and tuberculin skin test in routine screening for latent tuberculosis in patients with inflammatory bowel diseases.
abstract: BACKGROUND
  Screening for latent tuberculosis (LTB) including chest x-ray, tuberculin skin test (TST), and facultative whole blood interferon-γ assay (IGRA) is part of routine management in inflammatory bowel disease (IBD) patients before starting therapy with tumor necrosis factor (TNF)-α inhibitors. However, in patients with immunomodulators (IM) TST and IGRA might show limitations.
  
  
  METHODS
  We aimed to evaluate the results from an IGRA (QuantiFERON-TB Gold in Tube) and TST as well as their concordance in 208 consecutive IBD patients with indications for anti-TNF-α therapy. Associations of both tests with risk factors for LTB were determined by logistic regression.
  
  
  RESULTS
  During screening, 149 patients (71.6%) were under IM therapy. In 26 (12.5%) patients TST was positive, whereas 15 (7.2%) patients showed a positive result from IGRA. IGRA failed on samples from 16/208 (7.7%) patients, resulting in 192/208 (92.3%) patients in whom results from both screening tests were available. Correlation between IGRA and TST results was fair (84.9%, κ = 0.21). The presence of risk factors for LTB showed association with positive results of TST (odds ratio [OR] 3.7, 1.5-9.6) and IGRA (OR 3.5, 1.2-11.3). TST was associated furthermore with age (OR 1.06, 1.02-1.10) and signs indicative of LTB in chest x-ray (OR 4.9, 1.1-19.9). The IGRA was negatively influenced by IM therapy (OR 0.3, 0.1-0.9).
  
  
  CONCLUSIONS
  Our study reveals that results of IGRA are negatively affected by IM therapy. Thus, current guidelines for TB screening prior anti-TNF-α therapy appear inaccurate in patients under IM. Therefore, LTB screening might be best performed prior to initiation of IM treatment.
authors: Department of Internal Medicine III, Division of Gastroenterology and Hepatology, Vienna General Hospital, Medical University of Vienna, Vienna, Austria.
authors: Pavol
authors: P
authors: Papay
authors: Alexander
authors: A
authors: Eser
authors: Stefan
authors: S
authors: Winkler
authors: Sophie
authors: S
authors: Frantal
authors: Christian
authors: C
authors: Primas
authors: Wolfgang
authors: W
authors: Miehsler
authors: Gottfried
authors: G
authors: Novacek
authors: Harald
authors: H
authors: Vogelsang
authors: Clemens
authors: C
authors: Dejaco
authors: Walter
authors: W
authors: Reinisch
mesh_terms: D000328:Adult; D015331:Cohort Studies; D005260:Female; D006801:Humans; D007155:Immunologic Factors / Q000627:therapeutic use; D015212:Inflammatory Bowel Diseases / Q000175:diagnosis* / Q000188:drug therapy / Q000382:microbiology*; D007371:Interferon-gamma / Q000378:metabolism*; D055985:Latent Tuberculosis / Q000175:diagnosis* / Q000382:microbiology; D008297:Male; D008403:Mass Screening; D009169:Mycobacterium tuberculosis / Q000472:pathogenicity*; D011446:Prospective Studies; D013902:Radiography, Thoracic; D014374:Tuberculin Test
chemical_list: D007155:Immunologic Factors; D007371:Interferon-gamma