Interferon-γ release assays for the diagnosis of latent Mycobacterium tuberculosis infection.

In the absence of a gold standard for LTBI, the proper assessment of the TST, IGRAs or any other future tests intended for the diagnosis of LTBI should focus on determining their capability for predicting the development of active tuberculosis (TB), i.e. the positive and negative predictive values for progression to active TB. Alternative evidence, such as the diagnostic accuracy of the test in active TB cases, is not appropriate for assessing the test’s capability to predict the development of TB.