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P718 Risk of tuberculosis in patients with inflammatory bowel disease receiving biologics using two interferon-γ release assays as monitoring

R. de Francisco*1,2, M. Arias-Guillén3, A. Castaño-García1, I. Pérez-Martínez1, J. J. Palacios4, V. Rolle-Sóñora2, S. Martínez-González1, V. Jiménez-Beltrán1, N. Rodríguez-Ferreiro1, P. Flórez-Díez1, A. Suárez1,2, S. Riestra1,2

1Hospital Universitario Central de Asturias, Gastroenterology, Oviedo, Spain, 2Instituto de Investigación Sanitaria del Principado de Asturias, Oviedo, Spain, 3Hospital Universitario Central de Asturias, Respiratory, Oviedo, Spain, 4Hospital Universitario Central de Asturias, Microbiology, Oviedo, Spain

Background

Screening and treatment of latent tuberculosis infection (LTBI) before starting biological therapy in patients with inflammatory bowel disease (IBD) has decreased the risk of active tuberculosis. However, among patients with a negative baseline screening there is still a risk of developing tuberculosis. Positive conversion of tuberculin skin test and/or Interferon Γ Release Assay (IGRA) have been observed during biological treatment; however, there are not enough data to recommend monitoring for tuberculosis in this setting. Our aim was to assess the likelihood of detecting a positive seroconversion of a IGRA in IBD patients with negative baseline LTBI screening

Methods

Prospective, single-centre study in IBD patients attended at a Spanish IBD unit between 2009 and 2018. Patients with normal chest radiography, negative tuberculin skin test (most patients with booster), and one or two negative IGRAs (QuantiFERON/T-SPOT-TB) at baseline, and that receiving biological treatment, were included in the study. Two IGRAs were performed once a year during treatment with biologics. In all patients we assessed TB cases occurring during follow-up.

Results

250 patients were included (191 Crohn′s disease, 52 ulcerative colitis, 7 unclassified colitis), 137 males, mean age at the IBD diagnosis 30.5 years, mean age at the LTBI screening 38.2 years. In total, 8 patients (3.2%) (95% CI 1.5–6.4) presented a positive seroconversion of an IGRA (4 patients the first year, 1 the second year, 1 the third year, 1 the fourth year and 1 the fifth year). Four patients presented positive seroconversion of T-SPOT-TB, 2 patients presented positive seroconversion of QuantiFERON and, 2 patients positivized both IGRAs. Six of 741 T-SPOT-TB tests (0.81%, 95% CI 0.33–1.8) vs. 4 of 797 QuantiFERON tests (0.50%, 95% CI 0.1- 1.3) were positive (p not significant). After a follow-up of 949 patient-years, one patient developed an active tuberculosis; the overall incidence of active tuberculosis was 0.11 per 100 patient-years. The patient was asymptomatic and, Mycobacterium tuberculosis was isolated in sputum after two IGRAs resulted positive. Other seven patients with seroconversion were treated with isoniazid during biological therapy.

Conclusion

In an area of low incidence of tuberculosis, annual monitoring with two IGRAs in patients with IBD receiving biologics and who have had negative baseline LTBI screening is associated with a very low risk of active tuberculosis.