title: Factors Associated with Indeterminate and False Negative Results of QuantiFERON-TB Gold In-Tube Test in Active Tuberculosis.
abstract: BACKGROUND
  The sensitivities and specificities of interferon-gamma release assays (IGRAs) vary among different population studies, and the data on the routine use of IGRAs are limited. The aim of this study was to evaluate the role of QuantiFERON-TB Gold In-Tube (QFT-GIT) test in the diagnosis of active tuberculosis.
  
  
  METHODS
  We conducted a prospective study, enrolling 77 patients with suspected pulmonary tuberculosis (TB), at a secondary care teaching hospital in Seoul.
  
  
  RESULTS
  In total, 12 (15.6%) patients showed indeterminate results due to positive control failure on the QFT-GIT test. Indeterminate results were significantly associated with the elderly, history of the intensive care unit stay, lymphocytopenia, especially low CD4 count, increased C-reactive protein and decreased protein levels. Of the 77 patients, 44 (57.1%) were diagnosed with active pulmonary tuberculosis, and the percentage of false negative results of the QFT-GIT was 36.4% (vs. 31.8% with TST). In the TB group with >65 years old (n=12), the proportions of the indeterminate (33.3% vs. 3.1%) and the false negative results (58.3% vs. 25.0%) of the QFT-GIT were significantly higher than in the younger TB group (n=32).
  
  
  CONCLUSIONS
  Indeterminate and false negative results of QFT-GIT test were not infrequent in tuberculosis, especially in the elderly. Care should be considered for the interpretation with the elderly, immunocompromised, chronic and severely diseased patients.
authors.affiliation: Department of Internal Medicine, Seoul Medical Center, Seoul, Korea.
authors.forename: Kiwon
authors.initials: K
authors.lastname: Cho
authors.forename: Eunha
authors.initials: E
authors.lastname: Cho
authors.forename: Soohoon
authors.initials: S
authors.lastname: Kwon
authors.forename: Sanghyuk
authors.initials: S
authors.lastname: Im
authors.forename: In
authors.initials: I
authors.lastname: Sohn
authors.forename: Sookhee
authors.initials: S
authors.lastname: Song
authors.forename: Hyeok
authors.initials: H
authors.lastname: Kim
authors.forename: Suhyun
authors.initials: S
authors.lastname: Kim
keywords: Aged; Interferon-gamma Release Tests; Tuberculin Test