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.
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)].
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.
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.
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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: email@example.com.
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