title: Systematic review with meta-analysis: accuracy of interferon-gamma releasing assay and anti-Saccharomyces cerevisiae antibody in differentiating intestinal tuberculosis from Crohn's disease in Asians.
abstract: OBJECTIVE
  Distinguishing Crohn's disease (CD) from intestinal tuberculosis (ITB) is a clinical challenge. This meta-analysis assessed the clinical usefulness of Interferon-gamma releasing assay (IGRA) and anti-Saccharomyces cerevisiae antibody (ASCA) in the diagnosis of ITB and CD, respectively.
  
  
  METHODS
  Systematic search without language restriction was conducted in AMED, EBM, MEDLINE, EMBASE, and Google Scholar until September 2013. Studies that have evaluated performance of IGRA (QuantiFERON-TB Gold or T-SPOT.TB) or ASCA in distinguishing ITB from CD were eligible. Main outcome measures included sensitivity and specificity. Random-effects models were used to combine estimates from studies with significant heterogeneity. Area under the curve (AUC) was used to measure accuracy of the tests.
  
  
  RESULTS
  Eleven studies (five IGRA, three ASCA, three IGRA and ASCA) involving 1081 subjects were included. The pooled sensitivity, specificity, positive likelihood ratio, and negative likelihood ratio of IGRA for the diagnosis of ITB was 81% (95% CI, 75-86%), 85% (95% CI, 81-89%), 6.02 (95% CI: 4.62-7.83), and 0.19 (95% CI: 0.10-0.36), respectively. The AUC was 0.92. The pooled sensitivity and specificity of ASCA for the diagnosis of CD was 33% (95% confidence interval [CI], 27%-38%) and 83% (95% CI, 77-88%), respectively with an AUC of 0.58. T-SPOT.TB showed a higher sensitivity than QuantiFERON-TB Gold for the diagnosis of ITB.
  
  
  CONCLUSIONS
  IGRA and ASCA have a high specificity for the diagnosis of ITB. Both IGRA and ASCA may have a supplementary role in the differential diagnosis between ITB and CD when conventional workup is not diagnostic.
authors.affiliation: Department of Medicine and Therapeutics, Institute of Digestive Disease, State Key Laboratory of Digestive Disease, LKS Institute of Health Sciences, Chinese University of Hong Kong, Hong Kong.
authors.forename: Siew C
authors.initials: SC
authors.lastname: Ng
authors.forename: Hoyee W
authors.initials: HW
authors.lastname: Hirai
authors.forename: Kelvin K F
authors.initials: KK
authors.lastname: Tsoi
authors.forename: Sunny H
authors.initials: SH
authors.lastname: Wong
authors.forename: Francis K L
authors.initials: FK
authors.lastname: Chan
authors.forename: Joseph J Y
authors.initials: JJ
authors.lastname: Sung
authors.forename: Justin C Y
authors.initials: JC
authors.lastname: Wu
mesh_terms: D000908:Antibodies, Fungal / Q000097:blood*; D015415:Biomarkers / Q000097:blood; D003424:Crohn Disease / Q000175:diagnosis*; D003937:Diagnosis, Differential; D003938:Diagnostic Techniques, Digestive System; D006801:Humans; D007371:Interferon-gamma / Q000097:blood*; D012441:Saccharomyces cerevisiae / Q000276:immunology*; D012680:Sensitivity and Specificity; D014385:Tuberculosis, Gastrointestinal / Q000175:diagnosis*
chemical_list: D000908:Antibodies, Fungal; D015415:Biomarkers; D007371:Interferon-gamma
keywords: ASCA; Crohn's disease; IGRA; tuberculosis