Efficacy of Ustekinumab on Skin Reactions Induced by Tumor Necrosis Factor-Alpha Inhibitors in Patients with Inflammatory Bowel Disease

Introduction: Tumor necrosis factor-alpha (TNF-α) inhibitors sometimes induce skin reactions in patients with Crohn’s disease (CD) and ulcerative colitis (UC). Ustekinumab (UST) has been reported to be effective in treating TNF-α inhibitor-induced skin reactions. Here, we aimed to investigate the efficacy of UST on skin reactions and its long-term efficacy in the treatment of CD and UC. Methods: CD and UC patients who switched to UST due to skin reactions (skin reaction group) or secondary failure of TNF-α inhibitors (non-skin reaction group) in our hospital between June 2017 and September 2023 were included. The primary outcome was the efficacy of UST for skin reactions, classified as complete remission, partial remission, or no response. The secondary outcome was cumulative UST continuation, assessed using Kaplan-Meier analysis and Cox proportional hazards models. Inverse probability of treatment weighting (IPTW) was performed after adjusting for age, clinical remission status, and type of inflammatory bowel disease (CD or UC). Results: Eighty-two patients (CD, 68; UC, 14) were included; 20 developed skin reactions, most commonly psoriasiform dermatitis (30%). After switching to UST, 15 patients achieved complete remission of the skin reaction, and four achieved partial remission. After IPTW adjustment, the UST continuation rate did not differ significantly between groups (p = 0.205), and skin reactions were not associated with UST continuation (hazard ratio 0.55; 95% CI: 0.24–1.26; p = 0.159). Conclusions: UST was effective for 95% of TNF-α inhibitor-induced skin reactions without affecting long-term UST continuation, supporting its clinical utility.