title: Diagnostic values of the QuantiFERON-TB Gold In-tube assay carried out in China for diagnosing pulmonary tuberculosis.
abstract: BACKGROUND
  Interferon-release assays (IGRAs) for diagnosing active pulmonary tuberculosis (PTB) are not yet fully validated, particularly in high TB-endemic areas as the People's Republic of China (PRC). The aim of this report was to assess the performance of the QuantiFERON-TB Gold In-tube (QFT-GIT) and tuberculin skin test (TST), in addition to microbiological results, as contributors for diagnosing active PTB in the PRC.
  
  
  RESULTS
  A total of 300 PTB patients, 41 disease controls (DC) and 59 healthy community controls (HCC) were included prospectively between May 2010 and April 2011 from two provinces of the PRC (Heilongjiang and Zhejiang). The QFT-GIT and TST yielded an overall sensitivity for active TB of 80.9% and 86.2%, and a specificity of 36.6% and 26.8%, respectively. The province of origin and smear microscopy status did not significantly impact the diagnostic values for PTB. However, using the TST with a 10 mm cut-off point, a significantly higher proportion of LTBI was observed in the DC than the HCC (p=0.01). Discordant results between the QFT-GIT and TST were found among 1/3 of the PTB, HCC and DC. Two-thirds of the individuals presented TST-positive/QFT-GIT-negative discordant results. The TST-negative/QFT-GIT-positive result was not associated with age or bacillary load. Cumulative QFT-GIT and TST positive results increased the overall sensitivity (95.9%), but it was associated with a dramatic decrease of the overall specificity (24.8%) leading to a suboptimal PPV (80.1%) and a low NPV (61.1%).
  
  
  CONCLUSIONS
  The usefulness of the QFT-GIT to diagnose active TB in high TB-endemic countries remains doubtful because like the TST, the QFT-GIT cannot distinguish between LTBI and active TB. Used as single stand-alone tests, both the QFT-GIT and TST have very limited roles in the diagnosis of active PTB. However, the combined use of SM, the TST and QFT-GIT may allow for the exclusion of ATB.
authors: National Tuberculosis Reference Laboratory, Chinese Center for Disease Control and Prevention, Beijing, People's Republic of China.
authors: Hui
authors: H
authors: Xia
authors: Tuberculosis Control Center of Heilongjiang Province, Harbin, Heilongjiang, People's Republic of China.
authors: Xiaomen
authors: X
authors: Wang
authors: Zhejiang Provincial Center for Disease Control and Prevention, Binjiang District, Hangzhou, Zhejiang, People's Republic of China.
authors: Fabin
authors: F
authors: Li
authors: Fondation Mérieux, Lyon, France.
authors: Christophe
authors: C
authors: Longuet
authors: Fondation Mérieux, Lyon, France.
authors: Guy
authors: G
authors: Vernet
authors: Department of Epidemiology and Preclinical Research, L. Spallanzani National Institute for Infectious Diseases (INMI), Rome, Italy.
authors: Delia
authors: D
authors: Goletti
authors: National Tuberculosis Reference Laboratory, Chinese Center for Disease Control and Prevention, Beijing, People's Republic of China.
authors: Yanlin
authors: Y
authors: Zhao
authors: Service de Microbiologie, Hôpital Saint Louis, Assistance Publique-Hôpitaux de Paris, Paris VII Denis Diderot University, Paris, France.
authors: Philippe H
authors: PH
authors: Lagrange
mesh_terms: D000328:Adult; D016022:Case-Control Studies; D002681:China; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D011933:Reagent Kits, Diagnostic; D012680:Sensitivity and Specificity; D014397:Tuberculosis, Pulmonary / Q000175:diagnosis*; D055815:Young Adult
chemical_list: D011933:Reagent Kits, Diagnostic