Submucosal bowel wall layer thickness predicts endoscopic activity in Crohn's disease.

Abstract

Purpose: Gastrointestinal ultrasound is a well-established method for diagnosing and monitoring Crohn's disease (CD). The aim of this study was to investigate whether wall layer data measured on gastrointestinal ultrasound could predict endoscopic activity in CD.

Materials and methods: 64 CD patients underwent a gastrointestinal ultrasound examination and endoscopy ± 2 weeks apart in a single-center prospective study. Bowel wall thickness and the thickness of individual wall layers corresponding to the mucosa, submucosa and the proper muscle wall were measured and compared with the simple endoscopic score of Crohn's disease (SES-CD) in the most affected bowel segment where SES-CD >2 was defined as activity.

Results: There was increased absolute thickness of the mucosa (1.8 versus 1.1mm, p =0.001), submucosa (2.8 versus 1.2mm, p <0.001), and proper muscle (1.6 versus 1.1mm, p =0.006) in patients with endoscopic activity. After an ROC analysis, Youden's index suggested a 1.8 mm cut-off for submucosal thickness and disease activity resulting in a sensitivity of 90%, specificity of 78.3%, and accuracy of 84.9%. In contrast, a bowel wall thickness of 3 mm had a sensitivity of 97.3%, specificity of 52.0%, and accuracy of 79.0%. The submucosa was also relatively thicker (0.45 versus 0.36, p=0.008), while the proper muscle was relatively thinner (0.25 versus 0.34, p=0.001) in endoscopic activity.

Conclusion: Patients with Crohn's disease and endoscopic activity had an increased thickness of all bowel wall layers in affected areas. Measurements of the submucosa may be used to assess disease activity with results similar to bowel wall thickness.