Interrater reliability of the assessment of disease activity by gastrointestinal ultrasound in a prospective cohort of patients with inflammatory bowel disease

Objective Gastrointestinal ultrasound is a radiological investigation for monitoring patients with inflammatory bowel disease. However, the reliability of the findings depends on the reproducibility of results between different operators. Thus, the study aim was to assess the interrater reliability of gastrointestinal ultrasound in individuals with inflammatory bowel disease between gastroenterologists with varying GIUS experience. Methods Patients were prospectively recruited at the commencement of a new medical therapy for a baseline assessment, with a second assessment at the end of treatment induction (3 months). Consecutive, blinded ultrasounds were performed by two operators for every test. Gastrointestinal ultrasound examination included assessment of bowel wall thickness, vascularity, wall stratification assessment, mesenteric hyperechogenicity and lymphadenopathy. Results Forty-nine patients were recruited (Crohn's n = 27, ulcerative colitis n = 22) with 35 returning for a repeat assessment at 3 months. At baseline, the intraclass coefficient for bowel wall thickness was near perfect (0.882). By bowel segment, the closest correlation was in the terminal ileum and differences in bowel wall thickness were similar by disease subtype. All other ultrasound indices of disease activity demonstrated substantial to near-perfect agreement with Gwet's agreement coefficient: vascularity (0.681), wall stratification (0.685), mesenteric hyperechogenicity (0.841) and lymphadenopathy (0.633). Similar findings were seen at 3 months. Conclusion There is substantial agreement between operators of varying experience in gastrointestinal ultrasound findings in patients with Crohn's disease or ulcerative colitis and this is repeatedly demonstrated over time. Thus, a well-trained operator should be sufficient to assess disease activity in patients with inflammatory bowel disease. Copyright (C) 2021 Wolters Kluwer Health, Inc. All rights reserved.