How should I interpret an interferon gamma release assay result for tuberculosis infection?

Background: Interferon gamma release assays (IGRAs) are the first new diagnostic tests for latent tuberculosis (TB) infection (LTBI) since the century-old tuberculin skin test (TST). They are cell-mediated immune-based blood tests that have revolutionised LTBI diagnosis and are increasingly recommended by national guidelines.

Objectives: With the rapid expansion of the IGRA evidence-base in recent years, the limitations of IGRA and uncertainties in clinical interpretation of IGRA results have increasingly come into focus.