P381 Intestinal ultrasound in newly diagnosed Ulcerative Colitis predicts the need for colectomy

Abstract

Abstract Background Upon diagnosis of ulcerative colitis (UC), it remains challenging to predict who will have a severe disease course, ultimately necessitating colectomy. Predictive tools capable of risk-stratifying patients and individualize treatment are warranted. The aim of this study was to assess whether Intestinal ultrasound (IUS), performed at the onset of UC, could help predict the need for colectomy within the first year of diagnosis. Methods In a Danish prospective inception cohort, all new-onset adult patients with UC (including unclassified IBD) with left-sided or extensive colitis underwent IUS near the diagnostic endoscopy. The assessment included the International Bowel Ultrasound Segmental Activity Score (IBUS-SAS) and the bowel wall thickness (BWT) of the most inflamed segment. Besides IUS, we recorded age, gender, smoking, BMI, the Mayo endoscopic score (MES), the Simple Clinical Colitis Activity Index (SCCAI), and biomarkers hemoglobin (hgb), C-reactive protein (CRP), albumin and fecal calprotectin. Results During inclusion (May 2021 – April 2023), we included 193 UC patients with Montreal classification E2 or E3. In total, 12/193 (6%) underwent colectomy within the first year or during follow-up (min. 6 months). Baseline characteristics are presented in Table 1. Univariable analyses identified high MES, CRP, SCCAI, IBUS-SAS, and BWT, along with low Hgb and albumin, as significantly associated with an increased colectomy risk. Multivariable analysis with stepwise reduction identified only SCCAI (OR: 2.0, CI 1.2–3.3, p<0.005) and BWT (OR: 1.6, CI 1.1–2.3, p=0.01) as independent predictors. Through ROC analysis, BWT presented the highest accuracy (AUC: 0.89), and the optimal cut-off by Youden Index for colectomy prediction was > 6.1 mm. Combining all the significant non-IUS predictors, CRP, MES, SCCAI, hgb, and albumin yielded an AUC of 0.88. The highest accuracy was found by combining SCCAI and BWT, with an AUC of 0.94. Kaplan-Meier curve for colectomy-free survival is presented in Figure 1. Among patients with BWT>6.1mm, 18/21 (86%) started systemic steroids within the first week, compared to 43/125 (34%) of patients with BWT ≤ 6.1, p=0.007. Among patients with BWT > 6.1mm, 11/21 (52%) started biologics within the first 31 days, compared to 5/125 (4%) of patients with BWT≤6.1mm, p<0.001. Despite more aggressive treatment, 8/21 (38%) with BWT>6.1mm had a colectomy compared to 2/125 (2%) with BWT≤6.1mm.Conclusion IUS at UC onset, specifically BWT, is a robust predictor of colectomy risk within the first year of diagnosis. Combining clinical symptom scores with IUS enhances predictive accuracy. It can accurately identify patients at an increased risk of colectomy, guiding early treatment decisions for improved patient outcomes.