Interferon gamma release assay (IGRA). Significance in the diagnosis of latent tuberculosis infection and active tuberculosis

Interferon-gamma release assays (IGRAs) are in vitro immunoassays that have been introduced in recent years as an alternative to the tuberculin skin test (TST) for diagnosis of latent tuberculosis (LTBI). Due to their high specificity, especially in subjects with confounding factors such as BCG vaccination, IGRAS may rigorously reduce the number of persons with false-positive test results. Although pooled sensitivity is below 90%, IGRAs may be helpful for diagnosing active tuberculosis (TB) when combined with other tools. To detect LTBI before initiating TNF-alpha inhibitor therapy primarily only IGRAs are recommended.