Quantiferon-TB performs better in children, including infants, than in adults with active tuberculosis: a multicentre study

Immunological tests, including Quantiferon-TB Gold In-Tube (QFT-IT), represent an important aid for diagnosing active tuberculosis (TB) and latent TB infection in children, but concerns about their use in children < 5 years old persist.This is a multicentre retrospective study, comparing a population of 226 children to 521 adults with pulmonary and extra-pulmonary TB. The aim was to evaluate the QFT-IT performance analysing both qualitative and quantitative results by age, birthplace and disease localization.Compared to culture, QFT-IT sensitivity was 93.9%, 100% and 94.4% in children aged ≤ 2, 2-5 and 5-16 years old respectively, and was significantly higher than in adults (81.0%) (p<0.0001). The proportion of indeterminate tests in children (2.2%) was significantly lower compared to adults (5.2%) (p<0.0001). In children QFT-IT sensitivity was not affected by disease localization or birthplace (Italy-born vs. foreign-born). Interferon-gamma (IFN-γ) values in response to TB Antigen and Mitogen were significantly higher in children than in adults (TB Antigen: median 10 vs. 1.66 IU IFN-γ/ml; Mitogen: median 10 vs. 6.70 IU IFN-γ/ml, respectively) (p<0.0001).In summary, this study supports the use of QFT-IT as a complementary test for the diagnosis of paediatric TB even under 2 years of age. Our observations could be applicable to the new version of the test, Quantiferon-TB Gold Plus, which has recently been shown to have similar sensitivity in active TB, although data in children are still lacking.