Background: Anti-TNF treatments have improved the outcomes for patients with inflammatory bowel disease (IBD). However, they are associated with an increase in risk of Tuberculosis (TB). The aim of this study is to determine the proportion of latent TB infections (LTBI) in our IBD cohort treated with anti-TNFs and the management of these patients. We also examined the effect of different immunosuppressive drugs on the indeterminate rate of the interferon-gamma release assays (IGRA) in LTBI screening
Methods: We conducted a retrospective review of all patients treated with biologics between March 2007 and November 2015. Patient notes and electronic records were reviewed. LTBI screening was assessed using a risk assessment form, chest x-ray, and tuberculin skin test (TST) or IGRA for the screening for LTBI and the nature of the immunosuppressive treatment was documented.
Results: 732 patients with IBD were screened for LTBI before starting a biological treatment during the study period. 31 of 732 (4%) IBD patients were diagnosed and treated for LTBI with no significant side effects. 596 of 732 received their biologic treatment with a median delay of 86 days in initiating biologics. 6 of 596 patients who received biologic treatment developed active TB; 5 of whom were Caucasian.
247 patients were screened with an IGRA test. 6 were positive, 162 were negative and 79 patients were indeterminate. 45% with indeterminate IGRA had a repeat; half were negative and half remained indeterminate.
73% of the patients were receiving immunosuppressive (IMM) medication(s). There was a higher indeterminate rate of the IGRA in the IMM group compared to the no-IMM group (32% compared to 9%). The combination of steroids and thiopurines gave the highest rate of an indeterminate IGRA. High and low doses of steroids were equally likely to result in an indeterminate IGRA result.
Conclusions: 4% of patients screened had LTBI and 1% of patients treated with biologics developed active TB. Delays in initiating biologics due to LTBI screening may have detrimental effects on the IBD management. Almost one third of patients on immunosuppressants had an indeterminate IGRA, which supports the need for a guideline incorporating a risk stratification strategy based on factors such as country of birth and local TB prevalence. There is a need to remain vigilant for TB regardless of baseline LTBI results or epidemiological factors.