P0314 External validation of ultrasound scores for Crohn’s Disease: IBUS-SAS, BUSS, SUS-CD, Simple-US
Authors: Melotti L , Dussias N , Mazzotta E , Calabrese C , Scaioli E , Gionchetti P , Rizzello F 
Published: January 2025

Abstract

Background
Intestinal ultrasound (IUS) is widely accepted as a reliable tool to monitor Crohn’s Disease (CD). The most important parameters for the assessment of bowel inflammation are bowel wall thickness (BWT), parietal vascular signals evaluated by colour Doppler (CDS), loss of bowel wall stratification and increase in mesenteric inflammatory fat (i-fat). Some IUS scores have been proposed, but none have been formally accepted by international organizations for lack of external validation. The aims of our study were to evaluate the accuracy of the IUS scores available (BUSS, SUS-CD, Simple-US and IBUS-SAS) compared to endoscopy and to perform an external validation of endoscopy-based remission cut-offs available in literature, respectively 3.52, 1, 5.5 and 25.2. The remission cut-off for IBUS-SAS was taken from a secondary validation study1.

Methods
We conducted an observational, prospective, monocentric study. All CD patients that consecutively underwent an ileocolonoscopy according to clinical practice were considered for the study, and those meeting eligibility criteria were enrolled and performed an IUS within a maximum interval of 7 days. Patients with stoma or ileorectal anastomosis were excluded, as well as patients with moderate-severe obesity or concomitant acute gastroenteritis. For every intestinal segment evaluated, IUS scores were calculated and compared to endoscopy results considering as remission a Simple Endoscopic Score for Crohn’s Disease (SES-CD) ≤ 2. AUC was calculated for all scores. A p-value of &lt;0.05 was considered statistically significant.

Results
From June to September 2024 a total of 248 patients were considered for the study and 102 were enrolled. Seven were excluded due to the presentation of exclusion criteria. Ninety-five patients (110 intestinal segments) were analyzed. Median age was 45 years (IQR 35-55), approximately half of patients (48.4%) had isolated ileal disease and 56.8% were previously operated. Endoscopic activity was present in 40/110 cases (36.4%), with a median SES-CD of 2.21 (IQR 0-4). All scores correlated with endoscopy, as well as BWT and CDS alone (p&lt;0.001). In univariate analysis, BWT, CDS and i-fat predicted endoscopic activity, while only CDS was an independent risk factor in multivariate analysis (OR 5.35, p=0.04). A ROC analysis was performed for all scores with AUC values of 0.74, 0.72, 0.72, 0.68 for IBUS-SAS, BUSS, Simple-US and SUS-CD, respectively. Regarding cut-off values, sensitivity was 62.5, 70, 55 and 70%, and specificity 77.5, 71.5, 84.3 and 50%, respectively.

Conclusion
The US parameters BWT, CDS and i-fat correlated with endoscopic activity in CD patients. Our external validation demonstrated moderated accuracy of the available remission cut-offs of IUS scores.

References
1)G. Dragoni et al., «Correlation of Ultrasound Scores with Endoscopic Activity in Crohn’sDisease: A Prospective Exploratory Study», J Crohns Colitis, vol. 17, n. 9, pagg. 1387–1394, ott. 2023, doi: 10.1093/ecco-jcc/jjad068.