Concordance between the test of the tuberculin and Interferon Gamma Release Assay-IGRA in patients with immune-mediated inflammatory diseases

Introduction. The immunosuppressive therapies in the treatment of the immune-mediated inflammatory diseases (EIMI) predispose individuals to the tuberculosis, so the screening of latent tuberculosis infection (ITL) and the treatment reduces the likelihood of a progression to an active tuberculosis. The aim of the study was to analyze the concordance between the test of the tuberculin (PT) and "Interferon Gamma Release Assay-IGRA" in relation to the type of EIMI and the immunosuppressive treatment (IS). Material and methods. Transversal study of patients with EIMI candidates or in treatment IS forwarded to the ITL screening, from April 2017 until May 2018. The outcome variables were PT and IGRA. The explicative variables were: EIMI, IS, age, gender, prior BCG vaccination and tuberculosis risk factors. Results. A total of 146 patients were analyzed (33[22.69] vaccinated with BCG, 1 [0.7%] with a pre-diagnosis of tuberculosis, and 22 [15.1 0 4 from an endemic country). Kappa index (k) was 0,338 between PT and IGRA for the whole sample. A lower concordance was found in patients with the Crohn's disease (k=0.125), in the ones treated with corticosteroids (k=0.222), vaccinated with BCG (k=0.122) and in patients from tuberculosis endemic countries (k=0.128). Conclusion. The concordance between PT and IGRA is affected in patients with EIMI, and to a greater extent to patients with the inflammatory bowel disease, with the corticotherapy, with the BCG vaccination, or in the ones from endemic countries.