Performance of interferon-γ release assay for the diagnosis of active or latent tuberculosis in children in the first 2 years of age: a multicenter study of the Italian Society of Pediatric Infectious Diseases

Background: The diagnosis of latent or active tuberculosis in children is often challenging. Recently, interferon-gamma release assays have been licensed, but their diagnostic accuracy in young children remains questionable as frequent false-negative or indeterminate results have been reported. Methods: We performed a multicenter, retrospective study in children 0-24 months of age who were tested at least once with QuantiFERON-TB Goldin-tube (QTF-IT) +/- tuberculin skin test (TST), to analyze its use and performance in clinical practice. Results: Eight-hundred and twenty-three children (449 males, median age 13.5 months) were enrolled. QTF-IT sensitivity and specificity for active tuberculosis were 92.4% and 98.6%, respectively. Indeterminate tests (4.2 %) were not related to age (P = 0.838) or gender (P = 0.223); 32 children (91.4 %) with an indeterminate QTF-IT ultimately resulted uninfected. In the 616 subjects with valid paired results of QTF-IT and TST, sensitivity and specificity were comparable (91.1% vs. 85.1% and 98.1% vs. 97.9%, respectively). Diagnostic concordance between tests was higher in Bacillus Calm tte-Guerin nonvaccinated children (kappa = 0.802). A high rate of discordant tests was observed in latent infections. Conclusions: QTF-IT showed good sensitivity and specificity, and a low rate of indeterminate results in the first 2 years of life, supporting its use at this age. However, considering costs and the similar performance between QTF-IT and TST, it is reasonable to suggest the latter as first-line testing in young children. The complementary use of TST and interferon-gamma release assays may be considered in selected cases to improve the accuracy of testing.