Molecular Medicine & Therapeutics

Abstract

Context: This meta-analysis was performed to systematically evaluate two interferon gamma release assays (IGRAs): ELISA and ELISPOT along with Tuberculin Skin Test (TST) in the detection of latent tuberculosis infection. Methods: PUBMED, MEDLINE, and OVID data bases were searched between January 2000 and October 2012 for serial IGRA and TST results in screening LTBI among children. Meta-analysis was performed to estimate the sensitivity, specificity and predictive value of the two commercial IGRAs and TST. Results: A gradient of exposure among contacts was used as the gold standard for evaluating the sensitivity of the IGRA and TST. For IGRA, the positive result rates gradually decreased with the reduced degree of exposure in ten studies, and for TST, the same trend was seen in seven studies. In children with an 88.6% BCG vaccination rate, IGRA had a high specificity (88% for QFT-IT and 90% for T-SPOT, respectively). The pooled specificity of TST was only 65%. Two articles conducted a longitudinal cohort study to determine the prognostic value of positive IGRA and TST results for development of active tuberculosis, and suggested IGRA has a very high negative predictive value; children with positive IGRA results were 3.4 times more likely than those with negative results to develop active disease. Conclusion: Current evidence suggests that IGRA tests are likely to be specific tools to diagnose tuberculosis infection especially in children with BCG vaccination. Additional large cohort studies are needed to draw a clear conclusion of the prognostic value of the two tests.