P0483Intestinal ultrasound as a predictor of response to appendectomy in active ulcerative colitis

Abstract Background Appendectomy has emerged as a potential therapeutic option for active ulcerative colitis (UC).1,2 The recent COSTA trial reported a 33% clinical remission rate in therapy-refractory UC patients who underwent appendectomy, which was significantly higher than the control group receiving Janus kinase inhibitors (12%).3 Still, only a subset of patients benefit from appendectomy. In this study, we investigated whether appendiceal intestinal ultrasound (IUS) predicts response to appendectomy in active UC. Methods Participants from the Amsterdam UMC site of the COSTA trial were included in this sub-study (Clinicaltrials.gov number NCT03912714). UC patients with clinically and endoscopically confirmed active disease refractory to at least one advanced therapy underwent preoperative IUS of the appendix. Total appendiceal diameter (TAD), bowel wall thickness (BWT), layer-specific thickness and relative submucosal echogenicity (RSE) were assessed.4 Clinical response to appendectomy was defined as a ≥ 2 point reduction in the total Mayo score (TMS) and a ≥ 30% decrease from baseline without therapy failure at 12 months follow-up. Results Of the 55 participants of the IUS sub study, the appendix was visualized in 45 cases (82%). Clinical response was achieved in 18 of 45 patients (40%) with a visualized appendix. Clinical responders had a numerically higher TAD than non-responders (median 4.9 IQR, 3.4-6.3 vs 4.4 IQR, 3.7-5.1 mm, p = 0.524), while RSE (94.6 SD, 28.5 vs 115.5 SD 41.0 grayscale values, p = 0.05) and submucosal thickness (0.6 SD 0.3 vs 0.8 SD 0.3 p = 0.104) were lower in responders compared to non-responders (Table). We identified a TAD of ≥ 6 mm as the optimal cut-off for predicting clinical response with 38.9% sensitivity, 92.6% specificity and 78% positive predictive value (PPV). For non-response, submucosal thickness 0.75 mm had 50% sensitivity, 82.4% specificity, and similarly, RSE 111 grayscale values predicted non-response with 50.0% sensitivity, 70.6% specificity and 92% PPV. Multivariate logistic regression identified significant predictive parameters for clinical response: TAD ≥6 mm was associated with higher odds of response (odds ratio OR 19.6, 95% CI 1.69-227.5, p = 0.017), whereas RSE 111 grayscale value was associated with lower odds of response (OR 0.09, 95% CI 0.01-0.78, p = 0.028). Based on these findings, we developed a flowchart (Figure) illustrating a potential decision-making pathway for appendectomy in therapy-refractory UC patients. Conclusion In conclusion, we demonstrated that IUS can predict clinical response to appendectomy in active, therapy-refractory UC patients. References: 1. Sahami S et al. J Crohns Colitis 2019; DOI: 10.1093/ecco-jcc/jjy127. 2. Reijntjes MA, et al. Br J Surg 2024; DOI: 10.1093/bjs/znad425. 3. Visser E et al. The Lancet Gastroenterology DOI: 10.1093/ecco-jcc/jjaf158 Conflict of interest: Mr. Pruijt, Maarten: No conflict of interest Visser, Eva: No conflict of interest de Voogd, Floris: FdV has received consultancy fees from Pfizer and speaker fees from AbbVie, Janssen and Takeda Reijntjes, Maud: No conflict of interest Buskens, Christianne J.: Grant: C. Buskens has received an unrestricted grant from Boehringer Ingelheim and Roche Personal Fees: C. Buskens has received consultancy fees and/or speaker’s honoraria from Tillotts, Takeda, MSD and Janssen Gecse, Krisztina B.: Grant: Abbvie, Pfizer Inc, Celltrion and Galapagos/Alfasigma Personal Fees: Consultancy fees from AbbVie, ​Galapagos, Gilead, Immunic Therapeutics, Janssen Pharmaceuticals, Pfizer Inc., and Takeda and speaker’s honoraria from Celltrion, Eli Lilly, Janssen Pharmaceuticals, Pfizer Inc. and Takeda.