Tumor Necrosis Factor Inhibitors in Inflammatory Bowel Disease and Risk of Immune Mediated Inflammatory Diseases

BACKGROUND & AIMS: Tumor necrosis factor inhibitors (anti-TNF) are effective therapies for several immune -mediated inflammatory diseases (IMIDs). However, case reports have identified the paradoxi-cal occurrence of IMIDs in patients treated with anti-TNF. We studied the risk of rheumatoid arthritis, psoriasis, and hidradenitis suppurativa after the initiation of anti-TNF therapy for inflammatory bowel disease (IBD).METHODS: We conducted 2 nationwide cohort studies comprising all patients with IBD in Denmark (2005- 2018) and France (2008-2018). We obtained individual-level information on exposure to anti-TNF, diagnoses of IMIDs including rheumatoid arthritis, psoriasis, and hidradenitis suppu-rativa, and potential confounders from healthcare registers in the respective countries. We used Cox models to estimate hazard ratios (HRs) for the association between anti-TNF exposure and IMIDs and then pooled the estimates from the 2 cohorts. To test the robustness of our results, we performed an active comparator analysis of anti-TNF monotherapy vs azathioprine monotherapy. RESULTS: The Danish and French cohorts comprised 18,258 and 88,786 subjects with IBD, respectively, contributing a total of 516,055 person-years of follow-up. Anti-TNF was associated with an increased risk of rheumatoid arthritis, psoriasis, and hidradenitis suppurativa in both the Danish (HR, 1.66; 95% confidence interval [CI], 1.34-2.07) and the French cohort (HR, 1.78; 95% CI, 1.63-1.94), with a pooled HR of 1.76 (95% CI, 1.63-1.91). Anti-TNF was also associated with an increased risk of the outcomes when compared with azathioprine (pooled HR, 2.94; 95% CI, 2.33-3.70). CONCLUSIONS: In 2 nationwide cohorts of IBD patients, anti-TNF therapy was associated with an increased risk of rheumatoid arthritis, psoriasis, and hidradenitis suppurativa.