P601 Intestinal Ultrasound Correlates with Clinical, Biochemical, Endoscopic and Histologic Biomarkers in Patients with Ulcerative Colitis: a Cross-Sectional Study

Background Intestinal ultrasound (IUS) is emerging as a non-invasive monitoring tool in patients with ulcerative colitis (UC). Our goal was to correlate IUS with clinical, biochemical, endoscopic and histological activity. Methods Cross-sectional multicentric study of patients with left (E2) or extensive (E3) UC. Consecutive patients were included and clinical (Patient-Reported Outcome (PRO2) and Simple Clinical Colitis Activity Index (SCCAI)), biochemical (fecal calprotectin (FCal) and C-reactive protein (CRP)), endoscopic (Mayo endoscopic sub-score (sMayo)) and histological (Nancy score) activity were evaluated. IUS activity was characterized by Milan Ultrasound Criteria (MUC). Clinical, biochemical, ultrasonographic, endoscopic and histologic remission were defined as SCCAI≤2, FCal<250 ug/g, MUC<6.2, sMayo=0 and Nancy=0, respectively. All evaluations were performed within 1 month. Pathologist was blinded to endoscopic and IUS results. In patients in IUS remission, the sigmoid colon was considered for analysis. Results 58 patients with UC were included (55% men, with a mean-age of 38 (+/-17) years, 65% with E2 UC). Clinical, biochemical, ultrasonographic, endoscopic and histologic remission occurred in 53%, 53%, 53%, 31% and 12% of the patients, respectively. The most affected segment by both IUS and endoscopy was the sigmoid colon (34.5% and 41.4%, respectively). In our cohort, IUS activity had a strong correlation with PRO2 (r=0.778, p<0.001), SCCAI (r=0.810, p<0.001) and endoscopic activity (r=0.758, p<0.001), and a moderate correlation with FCal (r=0.517, p<0.001), CRP (r=0.402, p<0.001) and histological activity (r=0.475, p<0.001). We observed a consistent increase in the bowel wall thickness (BWT) and MUC score as the sMayo raised. Accordingly, patients with endoscopic activity presented higher BWT and MUC score, when compared to patients in endoscopic remission (Table 1). On the other hand, patients in IUS remission showed higher rates of clinical (90% vs 10%, p<0.001) biochemical (74% vs 26%, p<0.001) and endoscopic remission (94% vs 6%, p<0.001), with a trend towards higher rates of histologic remission (86% vs 14%, p=0.054). Conclusion In our cohort, IUS activity had a moderate to strong correlation with clinical, biochemical, endoscopic and even histologic activity. Additionally, patients with endoscopic activity presented worse IUS activity, suggesting this method as a reliable non-invasive monitoring tool in UC patients.