Inflammatory Bowel Disease Risk in Patients With Axial Spondyloarthritis Treated With Biologic Agents Determined Using the BSRBR-AS and a MetaAnalysis

Objective. To determine, among patients with axial spondyloarthritis (axSpA), whether the risk of inflamma-tory 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 differ-ence (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 asso-ciated 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 sta-tistically 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.

Automated summary

Among patients with axSpA, biologic therapies were associated with an increased risk of IBD compared to other therapies, based on observational studies. However, this association was not observed in placebo-controlled RCTs. Furthermore, the data did not suggest a higher risk of IBD with ETN compared to other anti-TNF therapies.