Active TB related to IGRA conversion in a dynamic cohort of patients with Inflammatory Bowel Disease receiving biological therapy, with up to 14 years of follow-up.

<bold>Goals:</bold> To determine the utility of repeated IGRAs annually compared to a single determination in the diagnosis of latent TB infection (LTBI). Determine the % of active TB in the cohort despite the use of IGRAs and prophylaxis. <bold>Methodology:</bold> Prospective cohort study, based on a dynamic cohort with dates of entry into the cohort from 2009 to 2021 (N = 456) and a prospective follow up to 2023. The prevalence of LTBI was obtained in the first year of inclusion (this is, the year of first screening of LTBI), as well as the % of seroconversion over the subsequent years, along with their 95% CI were obtained by the exact method. <bold>Results:</bold> The prevalence of latent tuberculosis infection in the year of inclusion (positive result in TST and / or at least one IGRA and / or booster) was 17.32% (N = 79/456); 95% CI (13.74%-20.91%). During the subsequent years of follow-up, a seroconversion was observed in 20 out of the 377 patients with a negative result in the year of inclusion; with a prevalence of seroconversion = 5.31%; 95% CI (2.91%-7.70%). Eleven patients out of the total of the cohort, developed an active TB, with a prevalence of active TB = 2.41%: 95%CI (0.89-3.93%). Three of the patients had received chemoprophylaxis. One developed pleural TB before the first year of follow-up. Genotyping of active TB showed that the origin was due to circulating strains <bold>Conclusions:</bold> The performance of the IGRAs annually is associated with a diagnostic income, since a seroconversion percentage of 5.78% has been observed. Despite the screening done with these tests and the associated QMP 11 patients ended up with active TB