TB status in a dynamic cohort of patients with Inflammatory Bowel Disease receiving immunosuppression treatment, with up to 8 years of follow-up

Goals: 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. Methodology: Prospective cohort study, based on a dynamic cohort with dates of entry into the cohort from 2009 to 2018 (N = 512), with a follow-up range therefore between 1 and 9 years. The prevalence of LTBI was obtained in the first year of inclusion, and the % of seroconversion over the subsequent years, along with its 95% CI obtained by the exact method. Results: The prevalence of latent tuberculosis infection (positve result in TST and / or at least one IGRA) was 17.8% (N = 91/512); 95% CI (14.4% -21.2%). In 4.3% (N = 18) of patients with a negative result in the first year of follow-up (N = 421), a seroconversion was observed; 95% CI (2.2% -6.3%). Of the total of the cohort, three patients developed active TB in 2017, with the prevalence of active TB of 0.4%; 95% CI (0.05-1.4%). Two of them had previously received QMP after a positive result in the follow-up. Conclusions: The performance of the IGRAs annually is associated with a diagnostic income, since a seroconversion percentage of 4.3% has been observed. Despite the screening done with these tests and the associated QMP, 3 patients ended up with active TB.