The evidence for greater sensitivity of interferon-γ release assays compared to tuberculin skin test in diagnosing latent mycobacterium tuberculosis infection

摘要

In their recent meta-analysis, Ge et al1 assessed performance characteristics of interferon-y release assays (IGRA) in the diagnosis of latent Mycobacterium tuberculosis infection in children compared to tuberculin skin tests (TST) as reference standard. The authors arrived at the conclusion that IGRA are both more sensitive and more specific compared to TST and that (for T-SPOT. TB) pooled sensitivities and specificities indicated a "missed diagnosis rate" of 6.9% and "misdiagnosis rate" of 23.3%. The data of the authors, however, only provide some indirect evidence supporting their conclusions regarding sensitivity and specificity and certainly do not allow conclusions regarding missed diagnosis or misdiagnosis: Using the tuberculin skin test as a reference standard does not allow conclusions about its comparative sensitivity or specificity. To compare sensitivity and specificity of IGRA and TST would require a third measure as a "gold standard" and surrogates used are proximity to index case or for active tuberculosis culture positivity.