Abstract
BackgroundThere are limited data comparing the performance of the two commercially available interferon gamma (IFN-γ) release assays (IGRAs) for the diagnosis of tuberculosis (TB) in children. We compared QuantiFERON-TB gold In Tube (QFT-IT), T-SPOT.TB and the tuberculin skin test (TST) in children at risk for latent TB infection or TB disease.Methods and FindingsThe results of both IGRAs were compared with diagnosis assigned by TST-based criteria and assessed in relation to TB contact history. Results from the TST and at least one assay were available for 96 of 100 children. Agreement between QFT-IT and T-SPOT.TB was high (93% agreement, κ = 0.83). QFT-IT and T-SPOT.TB tests were positive in 8 (89%) and 9 (100%) children with suspected active TB disease. There was moderate agreement between TST and either QFT-IT (75%, κ = 0.50) or T-SPOT.TB (75%, κ = 0.51). Among 38 children with TST-defined latent TB infection, QFT-IT gold and T-SPOT.TB assays were positive in 47% and 39% respectively. Three TST-negative children were positive by at least one IGRA. Children with a TB contact were more likely than children without a TB contact to have a positive IGRA (QFT-IT LR 3.9; T-SPOT.TB LR 3.9) and a positive TST (LR 1.4). Multivariate linear regression analysis showed that the magnitude of both TST induration and IGRA IFN-γ responses was significantly influenced by TB contact history, but only the TST was influenced by age.ConclusionsAlthough a high level of agreement between the IGRAs was observed, they are commonly discordant with the TST. The correct interpretation of a negative assay in a child with a positive skin test in clinical practice remains challenging and highlights the need for longitudinal studies to determine the negative predictive value of IGRAs.
Highlights
The detection and treatment of latent tuberculosis (TB) infection is a key strategy in the control of TB [1,2]
Conclusions: a high level of agreement between the interferon gamma (IFNc) release assays (IGRAs) was observed, they are commonly discordant with the TST
Interferon gamma release assays (IGRAs) incorporating Mycobacterium tuberculosis (MTB)-specific antigens have emerged as potential replacements for the century old tuberculin skin test (TST) [3]
Summary
The detection and treatment of latent tuberculosis (TB) infection is a key strategy in the control of TB [1,2]. Improved methods for detecting both latent TB infection and TB disease in children are needed. Interferon gamma release assays (IGRAs) incorporating Mycobacterium tuberculosis (MTB)-specific antigens have emerged as potential replacements for the century old tuberculin skin test (TST) [3]. The aim of this study was to compare the performance of two commercial IGRAs with TST in the diagnosis of children at risk for latent TB infection or with suspected active TB disease at a tertiary paediatric hospital. There are limited data comparing the performance of the two commercially available interferon gamma (IFNc) release assays (IGRAs) for the diagnosis of tuberculosis (TB) in children. We compared QuantiFERON-TB gold In Tube (QFTIT), T-SPOT.TB and the tuberculin skin test (TST) in children at risk for latent TB infection or TB disease
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