Diagnostic accuracy study of STANDARD TB-Feron FIA and STANDARD TB-Feron ELISA tests for tuberculosis infection diagnosis in Eastern European setting

Introduction Tuberculosis infection (TBI) is diagnosed based on a positive immune response to M. tuberculosis antigens. This study aimed to evaluate both the qualitative and quantitative performance of two novel IGRA-based tests, the STANDARD E TB-Feron ELISA (TB-Feron-ELISA) and the STANDARD F TB-Feron FIA (IFN-γ) (TB-Feron-FIA), and compare their results to those of QuantiFERON-TB Gold Plus (QuantiFERON). Methods At Chiril Draganiuc Phthisiopneumology Institute in the Republic of Moldova, we prospectively enrolled three cohorts of adults: healthy individuals with no known close contact with TB, patients with active tuberculosis (TB), and individuals with a history of TB. The active TB and past TB cohorts were used to assess the tests' sensitivity, while the healthy group was used to evaluate specificity. Both qualitative and quantitative results from the TB-Feron ELISA and TB-Feron FIA were compared with those of QuantiFERON. Results The TB-Feron-FIA demonstrated a sensitivity of 80.58 % (95 %CI: 71.90-87.06) in the active TB cohort and 82.93 % (95 %CI: 68.74-91.47) in the past TB cohort, with a specificity of 85.19 % (95 % CI: 73.40-92.30). The TB-Feron-ELISA showed a sensitivity of 80.58 % (95 %CI: 71.90-87.06) in the active TB cohort and 78.57 % (95 %CI: 64.06-88.29) in the past TB cohort, with a specificity of 85.19 % (95 %CI: 73.40-92.30). The agreement coefficient (κ) with QuantiFERON was 0.766 (95 %CI: 0.689-0.843) for TB-Feron-FIA and 0.809 (95 %CI: 0.739-0.880) for TB-Feron-ELISA. Conclusions Both the TB-Feron-ELISA and TB-Feron-FIA demonstrated good diagnostic accuracy for identifying individuals with TBI, comparable to the performance of QuantiFERON.