The study is an evaluation of the diagnostic performance of different tests and their association in order to confirm or exclude active tuberculosis.

Background : diagnostic methods to distinguish between latent TB infection (LTBI) and active TB disease remains challenging. Data are scarce concerning the positive predictive value of Current diagnostic approaches, including Interferon-Gamma Release Assay (IGRA) and chest radiography, which is often very low. Computed tomography (CT) scanning, although not recommended by the World Health Organization (WHO) for TB diagnosis, may be of high interest in our high-income low-burden countries. This study assess the performance of the combination of CT scanning and IGRA to diagnose active pulmonary TB and identifies discriminatory CT scan features indicative of active disease.

Methods : A retrospective study was conducted on 580 patients clinically suspected of TB or in contact with bacteriologically confirmed cases (index cases). Patients underwent IGRA testing, thoracic CT scans, and respiratory (or other organs) samples culture. CT scan findings were blindly analyzed, and a composite score combining significant radiological signs with IGRA results was constructed. Diagnostic performance measures, including sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV), were calculated.

Inclusion Criteria:

Major patients who received the following examinations at the Montpellier University Hospital for tuberculosis screening (clinical suspicion and/or contact with a person with active tuberculosis):

• Chest X-ray AND
• Chest CT scan AND
• Mycobacteriology examination of respiratory or tissue sample (direct/culture/GenXpert) AND
• IGRA test (Quantiferon)

Major patients screened for tuberculosis at the Montpellier University Hospital