Objective: To determine, among patients with axial spondyloarthritis (axSpA), whether the risk of inflammatory bowel disease (IBD) varies between patients treated with biologic therapies and those treated with other therapies and, specifically, whether the risk is higher in patients treated with etanercept (ETN).
Methods: The British Society for Rheumatology Biologics Register in Ankylosing Spondylitis (BSRBR-AS) was used to determine the incidence of IBD during follow-up and to calculate the incidence rate difference (IRD) per 1000 person-years (PY), between biologic treatment and other treatment groups. We then conducted a systematic review, involving observational studies and randomized controlled trials (RCTs), to perform a metaanalysis to quantify the difference in incidence of IBD between treatment groups.
Results: According to the BSRBR-AS, among people with axSpA, exposure to biologic therapy was associated with an increased incidence of IBD compared to those who were not exposed to biologic therapy (IRD 11.9, 95% CI 4.3-19.6). This finding was replicated across observational studies but was not seen in placebo-controlled RCTs (IRD 2.2, 95% CI -4.1 to 8.5). Data from the BSRBR-AS do not suggest that excess incidence of IBD is associated with exposure to ETN compared to other anti-tumor necrosis factor (TNF) therapies (IRD -6.5, 95% CI -21.3 to 8.5). RCTs and their extensions suggest a small-yet not statistically significant-absolute increased incidence associated with ETN of between 2.1 and 5.8 per 1000 PY compared to other anti-TNF therapies.
Conclusion: There was an excess risk of IBD among persons treated with biologics in observational studies. Only evidence from RCTs suggested that ETN was associated with an increased risk compared to other anti-TNF therapies, albeit with considerable uncertainty.
Keywords: axial spondyloarthritis; biologics; etanercept; inflammatory bowel disease; metaanalysis; tumor necrosis factor.
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