The effect of age on whole blood interferon-gamma release assay response among children investigated for latent tuberculosis infection.

OBJECTIVE: To evaluate the effect of age upon QuantiFERON-TB Gold-In-Tube (QFT-IT) assay outcome among children examined for latent tuberculosis infection (LTBI). STUDY DESIGN: A cross-sectional study was conducted among 761 children (mean age ± SD: 7.84 ± 4.68 years) evaluated for LTBI. Participants were examined with both tuberculin skin test and QFT-IT (Cellestis, Australia) and categorized into 4 age groups. Multivariate logistic and linear regressions were used to evaluate the association between selected demographic and patient characteristics upon the qualitative and quantitative QFT-IT outcomes. Agreement between the tuberculin skin test and QFT-IT within groups was evaluated with the κ statistic. RESULTS: QFT-IT indeterminate results occurred more frequently among young children (8.1%; P < .0001) and children (2.7%; P = .025) than adolescents (0.7%). Among QFT-IT positive patients, infants had higher mean (± SD) interferon-gamma (IFNγ) concentration than adolescents. QFT-IT positive (vs negative) outcome was associated with origin from a high tuberculosis endemicity setting (AOR = 4.54; 95% CI, 3.22-6.25) and lack of previous Bacille Calmette Guerin immunization (AOR = 2.70; 95% CI, 1.89-3.85), but not patient age (AOR = 0.96; 95% CI, 0.92-0.99). However, among QFT-IT positive patients, the IFNγ concentration was inversely associated with patient age (P = .009) and positively with mitogen response (P = .0002). Agreement between tests was not significantly different between younger and older children in the different risk groups. CONCLUSIONS: Qualitative QFT-IT assay results are not affected by patient age. However, indeterminate results occur more frequently among younger children. Among patients with LTBI the quantitative QFT-IT result (ie, IFNγ) is inversely associated with patient age.

The effectiveness of a 9-month regimen of isoniazid alone versus 3- and 4-month regimens of isoniazid plus rifampin for treatment of latent tuberculosis infection in children: results of an 11-year randomized study.

BACKGROUND: A 9-month course of isoniazid monotherapy is currently recommended for the treatment of latent tuberculosis infection (LTBI) and has been shown to be effective in both children and adults. Reduced compliance with this regimen has forced physicians to explore shorter regimens. The aim of this study was to compare 3- and 4-month combination regimens of isoniazid plus rifampin with a 9-month regimen of isoniazid monotherapy for the treatment of LTBI in children. METHODS: This prospective, randomized, controlled study was conducted over an 11-year period (1995-2005). In period 1 (1995-1998), 232 patients received isoniazid therapy for 9 months (group A), and 238 patients received isoniazid and rifampin for 4 months (group B). In period 2 (1999-2002), 236 patients were treated with isoniazid and rifampin for 4 months (group C), and 220 patients received the same regimen for 3 months (group D). All patients were observed for > or = 3 years. RESULTS: Overall compliance with treatment was good, but patients who received isoniazid monotherapy were less compliant than were those who received short-course combination therapy (P=.011, for group A vs. group B; P=.510, for group C vs. group D). No patient in any group developed clinical disease during the follow-up period. New radiographic findings suggestive of possible active disease were more common in patients who received isoniazid monotherapy (24%) than in those treated with shorter regimens (11.8%, 13.6%, and 11% for groups B, C, and D, respectively; P=.001 for group A vs. group B; P=.418 for group C vs. group D). Serious drug-related adverse effects were not detected. CONCLUSIONS: Short-course treatment with isoniazid and rifampin for 3-4 months is safe and seems to be superior to a 9-month course of isoniazid monotherapy.