IBUS-SAS Is a Highly Accurate Intestinal Ultrasound Score for Predicting Endoscopic Disease Activity in Ulcerative Colitis.

Abstract

Background: The international bowel ultrasound group-segmental activity score (IBUS-SAS) is a validated tool with high interobserver agreement for accurately detecting disease activity in Crohn's disease (CD). Here, we addressed whether the IBUS-SAS is also suitable to assess disease activity in ulcerative colitis (UC).

Methods: The IBUS-SAS and Limberg scores were determined in the sigmoid colon of patients with UC. The results were correlated to established scores of clinical, endoscopic and histologic disease activity (partial [pMS] and endoscopic [eMS] Mayo-Score, ulcerative colitis endoscopic index of severity [UCEIS], histologic Nancy index) and/or biomarkers of inflammation (C-reactive protein [CRP], fecal calprotectin). Sensitivity, specificity, positive (PPV) and negative predictive values (NPV) for IBUS-SAS and the Limberg score to predict endoscopic and histologic disease activity were computed by receiver operating characteristics (ROC)-analysis.

Results: Fifty-eight patients with UC were enrolled. The median IBUS-SAS was 34.8. It was significantly correlated with pMS, eMS, UCEIS, Nancy index, CRP and fecal calprotectin. On ROC-analysis, a cut-off of 15.9 was reached with 100% sensitivity and 80.0% specificity for the prediction of endoscopic activity, resulting in a PPV of 94.7% and an NPV of 100%. The Limberg score performed only slightly worse (100.0%, 60.0%, 89.9%, 100%, respectively). Comparable results were found regarding the Nancy index for sensitivity (93.9% vs. 93.9%), specificity (57.1% vs. 42.9%), PPV (91.4% vs. 88.9%) and NPV (65.7% vs. 59.0%).

Conclusions: This study highlights the potential of IUS for the non-invasive quantification of disease activity in UC and suggests that the IBUS-SAS should be considered as a diagnostic tool in trials and real-world management of UC.