OA17 The risk of inflammatory bowel disease in patients with axial spondyloarthritis treated with biologic agents: data from the BSR registry in axial spondyloarthritis (BSRBR-AS) and meta-analysis
Authors: Macfarlane Gary J , Biallas Renke , Dean Linda E , Jones Gareth T , Goodson Nicola , Rotariu Ovidiu 
Published: April 2022

Abstract

Background/Aims
Inflammatory bowel disease (IBD) is one of the extra-musculoskeletal manifestations associated with axial spondyloarthritis (axSpA). A previous meta-analysis reported a pooled prevalence of 6.8% (95% CI 6.1% to 7.7%). Amongst those commencing anti-TNFα therapy in BSRBR-AS it has been reported that patients with IBD were much less likely to have been prescribed etanercept (a soluble fusion protein) in comparison to the monoclonal antibodies in this cohort (adalimumab, certolizumab pegol and golimumab). A large study from Denmark of approximately 80,000 patients with an autoimmune disease (other than IBD) for which anti-TNFα therapy is an indication found a significant excess risk of IBD in those treated with etanercept, an excess which was not observed with other anti-TNFα agents. We therefore aimed to determine, amongst patients in BSRBR-AS, whether the risk of inflammatory bowel disease (IBD) varies between patients treated with biologic and other therapies, and whether specifically the risk is higher in patients treated with etanercept.

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) between biologic treatment and other treatment groups. We thereafter conducted a systematic review (involving observational studies and randomised controlled trials) to perform a meta-analysis to quantify the difference in incidence of IBD between treatment groups.

Results
In BSRBR-AS, among people with axSpA, exposure to biologic therapy was associated with an increased incidence of IBD compared to non-exposed patients (IRD 12.4 95% CI [5.5-19.4]). In meta-analysis, this finding was replicated across observational studies but not seen in placebo controlled RCTs IRD 2.2 95% CI (-4.1-8.5). Data from BSRBR-AS do not suggest that excess incidence of IBD is associated with exposure to etanercept compared to other anti-TNFα therapies (IRD -1.9 per 1000 py 95% CI [-15.2-11.5]). Trials and their extensions suggest a small (and not statistically significant) absolute increased incidence associated with etanercept of between 2.1 and 5.6 per 1000py compared to other anti-TNFα therapies.

Conclusion
An excess risk of IBD amongst persons treated with biologics is likely not causal but evidence from trials suggest that etanercept is associated with an increased risk compared to other anti-TNFα therapies, albeit with considerable uncertainty.

Disclosure
G.J. Macfarlane: Grants/research support; GJM is Chief Investigator a grant from BSR to fund the AS register. BSR received funds from Pfizer, AbbVie and UCB to support this work. R. Biallas: None. L.E. Dean: None. G.T. Jones: Grants/research support; GTJ is Co-Investigator on a grant from BSR to fund the AS register. BSR received funds from Pfizer, AbbVie and UCB to support this work. N. Goodson: Other; NG is Chair of the BSR Registers Committee. O. Rotariu: None.