To the Editors:
In their meta-analysis, Diel et al. [1] report a superior performance of interferon-γ release assays (IGRAs) for the diagnosis of latent tuberculosis infection (LTBI) compared with the tuberculin skin test (TST), the only other test available for diagnosing LTBI.
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 …