Abstract
BACKGROUND: Around one-quarter of the global population has latent tuberculosis infection (LTBI). If left untreated, LTBI has 5-10% lifetime risk of developing into TB. Interferon-gamma release Assays (IGRAs) are more sensitive than the tuberculin skin test for LTBI detection. However, the high cost and complexity of IGRAs are barriers to adoption in resource-constrained settings. This study evaluated the diagnostic performance of a more affordable IGRA, Standard E TB-Feron (TBE), among different risk groups in Bangladesh. METHODS: 532 participants of all age groups were enrolled from the TB Screening and Treatment Centers and Dhaka Hospital of icddr,b between June and September 2023. The participants were categorized into four risk groups: healthy people, healthcare workers/ attendants of TB patients, patients with microbiologically confirmed TB, and people with a history of TB. The diagnostic performance of TBE was compared to QuantiFERON-TB Gold Plus (QFT-Plus) for all groups. GeneXpert, culture, and microscopy were used to confirm TB microbiologically. RESULTS: TBE had an overall agreement of 85.9% (95% CI, 82.5% to 88.7%), positive percent agreement of 86.1% (95% CI, 80.6% to 90.5%), and negative percent agreement of 85.7% (95% CI, 81.3% -89.4%) with QFT-Plus. Among 81 culture-positive patients, TBE and QFT-Plus were positive for 60 (74.1%) and 62 (76.5%) respectively. Among healthy people, TBE and QFT results were positive for 49 (24.5%) and 59 (29.5%) respectively. Among health workers and contacts, TBE and QFT-Plus were positive for 79 (39.5%) and 73 (35.5%) respectively. CONCLUSION: We found a substantial agreement (Cohen's kappa of 0.71) between TBE and QFT-Plus in detecting LTBI across different groups, suggesting its potential as a cost-effective diagnostic tool. Implementation of TBE in routine clinical practice could increase accessibility to LTBI diagnosis, facilitating the timely initiation of preventative therapy, and leading to a reduction of active TB incidence.