title: Performance of interferon-gamma release assays in patients with inflammatory bowel disease: a systematic review and meta-analysis.
abstract: BACKGROUND
  Guidelines mandate screening for latent tuberculosis infection (LTBI) prior to anti-tumor necrosis factor (anti-TNF) therapy in patients with inflammatory bowel disease (IBD). However, many are already on immunosuppressive therapy (IST) that may affect the precision of the Tuberculin skin test (TST). Our aim was to assess the performance of the new interferon-gamma release assays (IGRAs) to detect LTBI in patients with IBD.
  
  
  METHODS
  MEDLINE and EMBASE were searched (up to June 2011) to identify studies evaluating the performance of IGRAs (QuantiFERON-TB Gold [QFT-2G], QuantiFERON-TB Gold In-Tube [QFT-3G] and T-SPOT.TB) in individuals with IBD. Forest plots and pooled estimates using random effects models were created where applicable.
  
  
  RESULTS
  Nine unique studies encompassing 1309 patients with IBD were included for analysis. The pooled concordance between the TST and QFT-2G/QFT-3G was 85% (95% confidence interval [CI] 77%-90%). The concordance of the TST and TSPOT.TB was 72% (95% CI 64%-78%). Studies assessing agreement reported more IGRA-/TST+ results versus IGRA+/TST- results. The pooled percentage of indeterminate results was 5% (95% CI 2%-9%) for QFT-2G/QFT-3G. TSPOT.TB showed similar results. Both positive QFT-2G/QFT-3G results (pooled odds ratio [OR] 0.37, 95% CI 0.16-0.87) and positive TST results (pooled OR 0.28, 95% CI 0.10-0.80) were significantly influenced by IST (both P = 0.02).
  
  
  CONCLUSIONS
  While it remains difficult to determine superiority between the IGRAs and the TST, both are negatively affected by IST. Therefore, screening prior to initiation of IST should be considered. Nevertheless, it is imperative that all patients receive screening prior to anti-TNF therapy.
authors.affiliation: Department of Medicine, Division of Gastroenterology, University of British Columbia, Vancouver BC, Canada.
authors.forename: Neal
authors.initials: N
authors.lastname: Shahidi
authors.forename: Yi-Tzu Nancy
authors.initials: YT
authors.lastname: Fu
authors.forename: Hong
authors.initials: H
authors.lastname: Qian
authors.forename: Brian
authors.initials: B
authors.lastname: Bressler
mesh_terms: D006801:Humans; D015212:Inflammatory Bowel Diseases / Q000150:complications*; D007371:Interferon-gamma / Q000378:metabolism*; D059425:Interferon-gamma Release Tests; D055985:Latent Tuberculosis / Q000175:diagnosis* / Q000209:etiology; D012196:Review Literature as Topic
chemical_list: D007371:Interferon-gamma