Background: Use of interleukin-17 inhibitors (IL-17i) in psoriasis has been associated with an increased risk of inflammatory bowel disease (IBD). However, the clinical significance of this association is not understood.
Objectives: To quantify the absolute risk of IBD in patients with psoriasis treated with IL-17i, stratified by known IBD risk factors.
Methods: Literature searches were performed to identify known IBD risk factors and the prevalences were quantified by a meta-analysis of proportions. The Bayesian model was used to estimate the probability of a new-onset or a flare of IBD in patients with psoriasis.
Results: The prevalence of Crohn disease (CD) or ulcerative colitis (UC) in the general psoriasis population was 0.0010. Use of IL-17i increased the risk of CD to 0.0037 and UC to 0.0028, translating to a number needed to harm (NNH) of 373 for CD and 564 for UC. In patients who had concomitant hidradenitis suppurativa, the use of IL-17i was associated with a decrease in NNH for CD and UC to 18 and 76, respectively, whereas for patients with a family history of IBD, the NNH values were 6 (for CD) and 10 (for UC).
Conclusions: In patients with no risk factors, the probability of IBD flare or onset during IL-17i treatment is negligible and additional IBD screening procedures are not indicated. In contrast, the patients with psoriasis who have hidradenitis suppurativa or first-degree family history of IBD as risk factors should be monitored for signs and symptoms of CD and UC during IL-17i therapy.