Evaluation of Diagnostic Performance of Three Commercial Interferon-Gamma Release Assays for <i>Mycobacterium tuberculosis</i>

Interferon-gamma release assays (IGRAs) gained attention for diagnosing latent tuberculosis infection (LTBI) due to their higher specificity compared to the tuberculin skin test (TST). However, IGRA performance varied across different populations. This study evaluated the diagnostic performance of three IGRA assays (TBF-FIA, TBF-ELISA, and QFT-Plus) in Ghana, comparing them among individuals exposed and unexposed to MTB infection. Conducted in TB clinics across three regions, this prospective and cross-sectional study included healthy individuals with no known TB exposure (unexposed group) and patients with confirmed active TB (exposed group). Blood samples were tested using all three assays per manufacturers’ guidelines. The TBF-ELISA showed 3.4% higher sensitivity, but 4.6% lower specificity compared to QFT-Plus. The TBF-FIA had a sensitivity of 78.5%-87.3% and a specificity of 82.9%-90.0%. These findings indicated that while the three IGRA assays offered similar diagnostic accuracy, variations in specificity and limited data on point-of-care assays like TBF-FIA required further investigation.