Validation of intestinal ultrasound scores in assessing endoscopic activity of colonic and small intestinal Crohn's disease in a southwest Chinese cohort: a retrospective cross-sectional study

Background: Recently, intestinal ultrasound (IUS) scores such as International Bowel Ultrasound Segmental Activity Score (IBUS-SAS) and Simple Ultrasound Score for Crohn's Disease (SUS-CD) have been established to evaluate disease activity in Crohn's disease (CD), but these require further external validation. This study thus aimed to compare recent IUS scores in patients with colonic or small intestinal CD in order to objectively assess their value and appropriate application.

Methods: This retrospective study consecutively enrolled data of patients with CD from October 2020 to November 2022. The endoscopic and ultrasound images were collected, and the affected segments were rescored according to endoscopic scores [Simple Endoscopic Score for Crohn's Disease (SES-CD), Rutgeerts score for patients who have undergone surgery, and the Lewis score for CD of the small intestine]; IUS scores were also collected, including the IBUS-SAS, Ultrasound Consolidated Score (UCS), SUS-CD, Simple Ultrasound Score (Simple US Score), and Bowel Ultrasound Score (BUSS). Subsequently, the correlation of IUS scores with endoscopic scores and the identification of disease activity was calculated. The Spearman rank correlation coefficient was used to calculate the correlation of parameters, and the Kruskal-Wallis test was used to compare different groups. Receiver operating characteristic (ROC) curve analysis was performed to evaluate the diagnostic efficiency of each score, and corresponding area under the curve (AUC), cutoff values, sensitivity, specificity, and 95% confidence intervals (CIs) were calculated.

Results: A total of 203 patients were included in this study. All scores correlated well with endoscopic scores and showed the ability to identify colonic CD activity with high sensitivity and specificity. Among all the scores, IBUS-SAS had the highest value overall and for colonic CD, with sensitivity of 92.7% and a specificity of 91.4% in identifying endoscopic activity and a sensitivity of 95.0% and a specificity of 88.2% in identifying severe endoscopic activity. In small intestinal CD, the UCS showed the highest correlation with endoscopic score, with a relative coefficient of 0.708. The corresponding cutoff values for identifying endoscopic activity and severe activity were also calculated.

Conclusions: Consistent with endoscopy, IUS scores are accurate in retrospective activity evaluation of CD, and suitable scores can be chosen according to the given circumstances.