title: Inadequate values from an interferon-gamma release assay for smear-negative tuberculosis in a high-burden setting.
abstract: OBJECTIVE
  To examine the usefulness of an interferon-gamma release assay (IGRA) for the diagnosis of smear-negative tuberculosis (TB) in China.
  
  
  METHODS
  A total of 624 patients with presumed pulmonary TB were enrolled prospectively and categorised as smear-negative TB, smear-positive TB or no TB. All patients were tested using T-SPOT.TB.
  
  
  RESULTS
  Both the smear-negative and smear-positive TB groups had significantly more spot-forming cells (SFCs) than the no TB group (all P < 0.001), while the smear-negative group had fewer SFCs than the smear-positive TB group (P < 0.001). The specificity of T-SPOT.TB was 60.4% (95%CI 53.4-67.1). The sensitivities of T-SPOT.TB in the smear-negative and smear-positive TB groups were respectively 81.4% (95%CI 75.7-86.0) and 93.2% (95%CI 87.6-96.4). The sensitivity in the smear-negative TB group was much lower than that in the smear-positive TB (P < 0.05).
  
  
  CONCLUSIONS
  The sensitivity of T-SPOT.TB was lower due the paucibacillary nature of the samples, and the specificity was lower due to the high prevalence of latent tuberculous infection in the smear-negative TB patients. The T-SPOT.TB test should only be used as a supplementary test and not as a single test to rule in or rule out smear-negative TB.
authors.affiliation: Beijing Key Laboratory for Drug-Resistant Tuberculosis Research, Beijing Chest Hospital, Capital Medical University, Beijing Tuberculosis and Thoracic Tumor Research Institute, Beijing, China.
authors.forename: F
authors.initials: F
authors.lastname: Liu
authors.affiliation: Beijing Key Laboratory for Drug-Resistant Tuberculosis Research, Beijing Chest Hospital, Capital Medical University, Beijing Tuberculosis and Thoracic Tumor Research Institute, Beijing, China.
authors.forename: F-J
authors.initials: FJ
authors.lastname: Du
authors.affiliation: Beijing Key Laboratory for Drug-Resistant Tuberculosis Research, Beijing Chest Hospital, Capital Medical University, Beijing Tuberculosis and Thoracic Tumor Research Institute, Beijing, China.
authors.forename: H-Y
authors.initials: HY
authors.lastname: Jia
authors.affiliation: Beijing Key Laboratory for Drug-Resistant Tuberculosis Research, Beijing Chest Hospital, Capital Medical University, Beijing Tuberculosis and Thoracic Tumor Research Institute, Beijing, China.
authors.forename: L-P
authors.initials: LP
authors.lastname: Pan
authors.affiliation: Beijing Key Laboratory for Drug-Resistant Tuberculosis Research, Beijing Chest Hospital, Capital Medical University, Beijing Tuberculosis and Thoracic Tumor Research Institute, Beijing, China.
authors.forename: X
authors.initials: X
authors.lastname: Zhang
authors.affiliation: Beijing Key Laboratory for Drug-Resistant Tuberculosis Research, Beijing Chest Hospital, Capital Medical University, Beijing Tuberculosis and Thoracic Tumor Research Institute, Beijing, China.
authors.forename: A-Y
authors.initials: AY
authors.lastname: Xing
authors.affiliation: Beijing Key Laboratory for Drug-Resistant Tuberculosis Research, Beijing Chest Hospital, Capital Medical University, Beijing Tuberculosis and Thoracic Tumor Research Institute, Beijing, China.
authors.forename: B-P
authors.initials: BP
authors.lastname: Du
authors.affiliation: Beijing Key Laboratory for Drug-Resistant Tuberculosis Research, Beijing Chest Hospital, Capital Medical University, Beijing Tuberculosis and Thoracic Tumor Research Institute, Beijing, China.
authors.forename: Q
authors.initials: Q
authors.lastname: Sun
authors.affiliation: Tuberculosis Department, Beijing Chest Hospital, Capital Medical University, Beijing Tuberculosis and Thoracic Tumor Research Institute, Beijing, China.
authors.forename: L-H
authors.initials: LH
authors.lastname: Nie
authors.affiliation: Tuberculosis Department, Beijing Chest Hospital, Capital Medical University, Beijing Tuberculosis and Thoracic Tumor Research Institute, Beijing, China.
authors.forename: H
authors.initials: H
authors.lastname: Li
authors.affiliation: Tuberculosis Department, Beijing Chest Hospital, Capital Medical University, Beijing Tuberculosis and Thoracic Tumor Research Institute, Beijing, China.
authors.forename: R-M
authors.initials: RM
authors.lastname: Liu
authors.affiliation: Beijing Key Laboratory for Drug-Resistant Tuberculosis Research, Beijing Chest Hospital, Capital Medical University, Beijing Tuberculosis and Thoracic Tumor Research Institute, Beijing, China.
authors.forename: Y
authors.initials: Y
authors.lastname: Ma
authors.affiliation: Beijing Key Laboratory for Drug-Resistant Tuberculosis Research, Beijing Chest Hospital, Capital Medical University, Beijing Tuberculosis and Thoracic Tumor Research Institute, Beijing, China.
authors.forename: Z-D
authors.initials: ZD
authors.lastname: Zhang
mesh_terms: D000328:Adult; D000368:Aged; D015415:Biomarkers / Q000032:analysis; D002681:China / Q000453:epidemiology; D058501:Enzyme-Linked Immunospot Assay; D005260:Female; D006801:Humans; D007371:Interferon-gamma / Q000032:analysis*; D059425:Interferon-gamma Release Tests; D008297:Male; D008875:Middle Aged; D009169:Mycobacterium tuberculosis / Q000276:immunology* / Q000302:isolation & purification*; D011237:Predictive Value of Tests; D011446:Prospective Studies; D015203:Reproducibility of Results; D013183:Sputum / Q000382:microbiology*; D014397:Tuberculosis, Pulmonary / Q000175:diagnosis* / Q000453:epidemiology / Q000276:immunology / Q000382:microbiology
chemical_list: D015415:Biomarkers; C573415:IFNG protein, human; D007371:Interferon-gamma