External validation and comparison of simple ultrasound activity score and international bowel ultrasound segmental activity score for Crohn's disease.

BACKGROUND: Intestinal ultrasound (IUS) is a non-invasive tool for monitoring Crohn's disease (CD) activity. Recently, sonographic activity scores, including the International Bowel Ultrasound Segmental Activity Score (IBUS-SAS) and Simple Ultrasound Activity Score for CD (SUS-CD), were developed. This study aimed to assess their clinical application value.

METHODS: This retrospective study enrolled patients with CD from March 2021 to June 2022. The diagnostic performance of the ultrasound scores was evaluated using the simplified endoscopic score for CD (SES-CD). Correlations of ultrasound scores with SES-CD, CD activity index (CDAI), and inflammatory biomarkers were assessed. Inter-rater reliability was compared.

RESULTS: In total, 140 patients were included. The IBUS-SAS for evaluating disease activity had an area under the curve (AUC) of 0.895, sensitivity of 85.4%, and specificity of 82.4% for the cut-off value of 48.7. The SUS-CD revealed an AUC of 0.835, sensitivity of 92.7%, and specificity of 64.7% for the cut-off value of 2.5. The IBUS-SAS and SUS-CD were positively correlated with SES-CD ( r  = 0.511 and 0.534, respectively). The scores correlated significantly with the CDAI and inflammatory biomarkers (all p  < 0.01). The IBUS-SAS was more strongly correlated with CDAI ( r  = 0.666 vs 0.486) and C-reactive protein ( r  = 0.645 vs 0.434) than the SUS-CD. The intraclass correlation coefficient (ICC) of the IBUS-SAS and SUS-CD between the two sonologists was excellent (ICC = 0.96 and 0.78, respectively).

CONCLUSION: Both the IBUS-SAS and SUS-CD can evaluate disease activity in CD and exhibited a significant correlation with activity indices and inflammatory biomarkers.

CLINICAL TRIAL REGISTRATION: ChiCTR2200055221.