title: Changes in QuantiFERON®-TB Gold In-Tube results during treatment for tuberculous infection.
abstract: METHODS
  Randomised trial comparing 9 months of isoniazid with 4 months of rifampicin for the treatment of high-risk tuberculin skin test positive subjects in Rio de Janeiro, Brazil.
  
  
  OBJECTIVE
  To compare QuantiFERON®-TB Gold In-Tube (QFT-GIT) responses before and 1, 4 and 9 months after starting treatment for latent tuberculous infection (LTBI) according to adherence to one of the two regimens.
  
  
  METHODS
  Participants in the trial were invited to undergo serial QFT-GIT. Within-subject differences at different time points were analysed as quantitative responses and categorised as positive or negative using different cut-off points.
  
  
  RESULTS
  Of 215 participants, 118 completed treatment, of whom 58 underwent all three tests; and 97 did not complete treatment, of whom 10 underwent all tests. After 1 month of treatment, there was no significant difference in QFT-GIT response between the groups. After 4 and 9 months, reversions were more frequent in non-adherent subjects. Marked within-subject fluctuations were observed. No cut-off point could be established at which QFT-GIT responses were consistently positive or associated with adherence or type of treatment.
  
  
  CONCLUSIONS
  Frequent within-subject variability in QFT-GIT responses, not associated with LTBI treatment, makes it difficult for clinicians to interpret QFT-GIT conversions and reversions.
authors.affiliation: Medical School and Post-Graduate Health Education Program, Gama Filho University, Rio de Janeiro, Rio de Janeiro, Brazil.
authors.forename: M L
authors.initials: ML
authors.lastname: Bastos
authors.forename: D
authors.initials: D
authors.lastname: Menzies
authors.forename: M T C T
authors.initials: MT
authors.lastname: Belo
authors.forename: E G
authors.initials: EG
authors.lastname: Teixeira
authors.forename: S T
authors.initials: ST
authors.lastname: de Abreu
authors.forename: P R Z
authors.initials: PR
authors.lastname: Antas
authors.forename: A
authors.initials: A
authors.lastname: Trajman
mesh_terms: D000328:Adult; D000995:Antitubercular Agents / Q000008:administration & dosage / Q000627:therapeutic use*; D001938:Brazil; D005260:Female; D006801:Humans; D059425:Interferon-gamma Release Tests; D007538:Isoniazid / Q000008:administration & dosage / Q000627:therapeutic use*; D055985:Latent Tuberculosis / Q000188:drug therapy* / Q000382:microbiology; D008297:Male; D055118:Medication Adherence; D008875:Middle Aged; D012293:Rifampin / Q000008:administration & dosage / Q000627:therapeutic use*; D013997:Time Factors; D016896:Treatment Outcome; D014374:Tuberculin Test; D055815:Young Adult
chemical_list: D000995:Antitubercular Agents; D007538:Isoniazid; D012293:Rifampin