Background: Interferon-γ release assays (IGRAs) have been recently developed for the diagnosis of tuberculosis (TB) infection. The aim of the present study was to evaluate the performance of an enzyme-linked immunosorbent assay (ELISA)-based IGRA for detecting TB in children.
Methods: A prospective study in 336 children at risk for TB infection was carried out. All children were tested with tuberculin skin test (TST) and a commercial ELISA-based IGRA [QuantiFERON-TB Gold In-Tube (Cellestis)].
Results: TST were positive in 58 of 336 (17.3%) and IGRA in 60 of 336 (17.9%) children. Two (0.6%) IGRA results were indeterminate. The overall agreement between the 2 tests was intermediate (86.2%, κ = 0.533). IGRA was positive in 15 of 16 (93.8%) children with active pulmonary TB. The discordant pattern IGRA−/TST+ was significantly associated with Bacille Calmette-Guérin (BCG) vaccination. Among IGRA+ children (excluding cases of TB disease), TST− were significantly younger than TST+ children.
Conclusions: The good agreement between positive IGRA and active TB disease suggests a good sensitivity of IGRA. Discrepancies between IGRA and TST can be a result of higher specificity of IGRA that is not influenced by previous BCG vaccination. IGRA may be more sensitive in children younger than 48 months.
From the Department of Pediatrics, University of Florence, Anna Meyer University Children’s Hospital, Florence, Italy.
Accepted for publication January 2, 2009.
Address for correspondence: Maurizio de Martino, MD, Department of Pediatrics, University of Florence, Anna Meyer University Children’s Hospital, Viale Pieraccini 24, I-50139 Florence, Italy. E-mail: firstname.lastname@example.org.
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