title: Reversion rates of QuantiFERON-TB Gold are related to pre-treatment IFN-gamma levels.
abstract: OBJECTIVE
  The quantitative interferon (IFN)-gamma in response to Mycobacterium tuberculosis-specific antigens declines in tuberculosis patients after starting treatment, however, in some cases remains high despite clinical improvements. Our aim was to evaluate clinical parameters associated with remaining QuantiFERON-TB Gold (QFT-G) positive after treatment.
  
  
  METHODS
  A prospective cohort study of 101 culture-positive, positive QFT-G, HIV-uninfected patients with pulmonary tuberculosis. QFT-G was performed at diagnosis, at the end of intensive phase, at treatment completion, and 5-7 months post-treatment completion.
  
  
  RESULTS
  There were 80 patients with complete results, 34 (43%) remaining QFT-G positive and 46 (58%) reverting to QFT-G negative at the 5-7 month post-treatment time point. There was a significant decline in IFN-gamma levels in response to both CFP-10 and ESAT-6 with tuberculosis treatment. Multivariate analysis revealed significant associations between IFN-gamma levels detected before treatment and remaining QFT-G positive post-treatment after adjustment for smear status, presence of cavitation, and positive sputum culture two months after starting treatment.
  
  
  CONCLUSIONS
  Quantitative QFT-G responses drop significantly in active tuberculosis patients undergoing treatment, with almost 60% becoming test negative. Reversion to a negative QFT-G result was closely associated with the magnitude of the IFN-gamma response prior to treatment and increasing age.
authors.affiliation: Center for Respiratory Disease, National Hospital Organization, Tokyo National Hospital, Tokyo, Japan. komiyakh1@oita-u.ac.jp
authors.forename: Kosaku
authors.initials: K
authors.lastname: Komiya
authors.forename: Haruyuki
authors.initials: H
authors.lastname: Ariga
authors.forename: Hideaki
authors.initials: H
authors.lastname: Nagai
authors.forename: Atsuyuki
authors.initials: A
authors.lastname: Kurashima
authors.forename: Syunsuke
authors.initials: S
authors.lastname: Shoji
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Ishii
authors.forename: Yutsuki
authors.initials: Y
authors.lastname: Nakajima
mesh_terms: D000328:Adult; D000367:Age Factors; D000368:Aged; D000942:Antigens, Bacterial; D000995:Antitubercular Agents / Q000627:therapeutic use; D023801:Directly Observed Therapy; D005260:Female; D006801:Humans; D007371:Interferon-gamma / Q000032:analysis*; D007564:Japan; D008297:Male; D008875:Middle Aged; D009169:Mycobacterium tuberculosis / Q000276:immunology*; D016133:Polymerase Chain Reaction; D011446:Prospective Studies; D013183:Sputum / Q000382:microbiology; D016896:Treatment Outcome; D014397:Tuberculosis, Pulmonary / Q000175:diagnosis* / Q000188:drug therapy
chemical_list: D000942:Antigens, Bacterial; D000995:Antitubercular Agents; D007371:Interferon-gamma