P955 The effect of appendicectomy on the clinical course of Ulcerative Colitis: Preliminary results

Abstract

Abstract Background Emerging evidence indicates an immunomodulatory role of the appendix in ulcerative colitis (UC). Previous studies have suggested a beneficial effect of appendicectomy in inducing and maintaining remission. Therefore, appendicectomy may be considered as an alternative or adjunctive treatment in UC. Aim To evaluate the efficacy of appendicectomy in maintaining remission in UC patients. Methods Adult patients with established UC in complete clinical and endoscopic remission (defined as Mayo score <3 with endoscopic subscore of 0 or 1) following medical induction treatment for disease relapse within 12 months prior to randomisation, were enrolled in the Netherlands and United Kingdom. Patients were randomised (1:1) to undergo appendicectomy (intervention group) or continue maintenance medical therapy (control group). The primary outcome was the one-year UC relapse rate (defined as a total Mayo-score score ≥5 with endoscopic subscore of ≥2). To detect a clinically relevant decrease in relapse rate from 40% to 20%, 82 patients per study arm were needed to achieve 80% power. The last patient was included in September 2022, so analysis of the primary outcome parameter is expected to start soon. Trial progress, including the accumulated number of (serious) adverse events (SAE) in both groups, were presented annually to the Data Safety Monitoring Board. Therefore safety data is available. Results In total, 99 patients were included in the intervention group and 99 patients in the control group. There were 86 males and 112 females, with a median age of 41 years (IQR 33-52). Baseline characteristics were comparable in both groups, with the majority of patients having proctitis (38.9%) or left sided colitis (35.9%). Three SAEs were reported in the appendicectomy group, 2 of which were related to the surgical procedure (reintervention for obstructive ileus and postoperative hematoma) and one hospitalisation for clostridium infection. One SAE was reported within the first year in the control group (appendicitis). The one-year reported colitis-associated adverse event rate was significantly lower in the appendicectomy group when compared to the control group (46.4% vs. 63.9%, P=0.02). During follow up there were no colectomies in the appendicectomy group, whereas three patients underwent colectomy for therapy-refractory disease in the control group. Conclusion Appendicectomy in patients with UC has the possibility to decrease the rate of colitis-associated (serious) adverse events. These results suggest that the final analysis of the primary outcome parameter (relapse rate) could demonstrate that appendicectomy is superior to standard medical therapy alone in maintaining remission in these patients.