KC Chang, ECC Leung, CC Leung

Abstract

Objective and methods: To evaluate interferon-gamma release assays (IGRA) in childhood tuberculosis, a systematic review was conducted by searching MEDLINE. Results: Seventeen relevant articles were included, all using surrogate measures (positive rate in culture-confirmed tuberculosis and negative rate among low-risk subjects) for tuberculosis infection. Only one paper contained data for estimating likelihood ratios for the tuberculin skin test (TST) and IGRA among predominantly BCG-unvaccinated paediatric subjects. The positive and negative likelihood ratios (95% confidence interval) were, respectively, 5.5 (2.3-13.2) and 0.44 (0.28-0.71) for TST with 15 mm cut-off; 74.9 (4.8-1181) and 0.09 (0.03-0.29) for QuantiFERON-TB Gold in-Tube; and 37.1 (5.3-258) and 0.07 (0.02-0.28) for T-SPOT.TB tests. Predictive values varied in different clinical and epidemiological settings. Unlike TST, test performance of IGRA was not affected by BCG vaccination status. Conclusion: TST may still play an important role in targeted contact investigation and clinical management, although IGRA may outperform TST in some settings.