Changes in QuantiFERON registered -TB Gold In-Tube results during treatment for tuberculous infection

• Published in: The international journal of tuberculosis and lung disease Vol. 17; no. 7; pp. 909 - 916
• Main Authors: Bastos, M L, Menzies, D, Belo, MTCT, Teixeira, E G, de Abreu, ST, Antas, PRZ, Trajman, A
• Format: Journal Article
• Language: English
• Published: 01.07.2013
• Subjects: Mycobacterium; Brazil, Rio de Janeiro; Brazil
• ISSN: 1027-3719

SETTING: 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. OBJECTIVES: To compare QuantiFERON registered -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. DESIGN: 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. CONCLUSION: 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.