P0949Intestinal ultrasound activity scores correlate with clinical disease activity but not fecal calprotectin in Ulcerative Colitis: real-world data from Sweden

Abstract Background Intestinal ultrasound (IUS) is a validated, non-invasive imaging tool for assessing inflammatory bowel disease (IBD). Activity scores derived from IUS, such as the International Bowel Ultrasound Segmental Activity Score (IBUS-SAS) and Milan Ultrasound Criteria (MUC), have shown promise, but their real-world correlation with clinical and biochemical markers in ulcerative colitis (UC) has not been fully evaluated. In this study, we aimed to evaluate the applicability of IUS in monitoring disease activity in UC. Methods We retrospectively reviewed UC patients who underwent IUS at the GI-Ultrasound Unit, Karolinska University Hospital, between October 2023 and April 2025. Demographic characteristics, disease extent, partial Mayo (p-Mayo) score, IUS parameters, and biochemical markers were collected. In all patients, the IBUS-SAS and MUC score were determined. All IUS examinations were performed by a single experienced gastroenterologist. Statistical analyses were performed in RStudio using Kendall’s τ, Spearman’s ρ, logistic regression, and ROC analysis. Results Twenty-seven UC patients were included (median age 37.6 years, 37.04% male, 62.96% female). Pancolitis was present at 74.1 % (20/27) and left-sided colitis in 25.9 % (7/27). Fecal calprotectin (FC) was available in 17 (62.96%) cases. Median p-Mayo score was 3.37 (0-9), median IBUS-SAS 15.34(8–53), median MUC 4.73 (2.8-13.2). IBUS-SAS correlated significantly with p-Mayo (τ = 0.43; p = 0.0007), as did MUC (τ = 0.41; p = 0.0009). Correlations with FC were weak both for IBUS-SAS (ρ = 0.1825; p = 0.49875) and MUC (ρ = 0.09; p = 0.74). In a logistic regression model predicting active disease (p-Mayo 2) using log-transformed IBUS-SAS, both the intercept (β0 = –4.34, p = 0.036) and the IBUS-SAS coefficient (β = 1.82, p = 0.037) were statistically significant. The odds ratio for log (IBUS-SAS) was 6.16, indicating that higher IUS scores were associated with markedly increased odds of clinical activity. ROC curve analysis identified an optimal IBUS-SAS threshold of 11.28, yielding sensitivity 57 % and specificity 92 % (AUC ≈ 0.8). Conclusion In this real-world cohort, both IBUS-SAS and MUC demonstrated strong correlation with clinical disease activity, supporting their potential as practical, non-invasive monitoring tools in UC, and showed superiority compared with FC. Conflict of interest: Rellou, Sofia: No conflict of interest Kordalis, Leonidas: No conflict of interest Petrousis, Grigorios: No conflict of interest Bilican, Gülden: I have no conflicts of interest to declare. Hedin, Charlotte Rose: Grant: C. R. H. Hedin has received specific project grants from Takeda and Tillotts. Personal Fees: C. R. H. Hedin served as a speaker and/or advisory board member for AstraZeneca, Abbvie, Dr Falk Pharma and the Falk Foundation, Galapagos, Janssen, Lilly, Pfizer, Ferring, Takeda, Tillotts Pharma, and received grant support from Tillotts and Takeda. These fees are invoiced by her employer. Bresso, Francesca: No conflict of interest Haas, Stephan L.: SLH served as a speaker and/or advisory board member for Celltrion, Ferring, Janssen, Lilly, Mediahuset, Pfizer, Santax Medico, Takeda, and Tillotts Pharma.