P199 External validation of Intestinal Ultrasound score: IBUS-SAS with clinical (CDAI), biomarkers and endoscopic scoring system (SES-CD)

Abstract

Abstract Background Intestinal ultrasound (IUS) is a non-invasive tool for assessing disease activity in patients with Inflammatory bowel disease. International Bowel Ultrasound Segmental Activity Score (IBUS-SAS) is a comprehensive score proposed by an expert consensus with good reliability. We aim to assess the correlation of the IBUS-SAS with clinical and endoscopic scores and biomarkers in patients with Crohn’s disease (CD) in a point-of-care setting. Methods This retrospective study was conducted from October 2021 to September 2023. All patients with CD who underwent colonoscopy at initial presentation or assessing disease activity on follow-up were included. At the clinic visit, Crohn’s disease activity index (CDAI), C-reactive protein levels (CRP), Faecal calprotectin (FC) were documented. IUS was performed in the clinic and IBUS-SAS was documented. A colonoscopy was done within 1 week of the clinic visit. Endoscopic disease activity was documented using Simple Endoscopic Score in Crohn’s disease (SES-CD). Statistical Analysis Pearson’s correlation was performed between IBUS-SAS and the clinical and endoscopic scores and the biomarkers. ROC analysis was done to assess the threshold value of IBUS-SAS to predict the presence of endoscopic disease activity. Results 181 patients were included in the study. In patients with clinical remission, the median IBUS-SAS was 8 (± 23.5). The median IBUS-SAS was 62 (± 21.47), 70 (± 15.47) & 64 (± 0.58) in patients with mild, moderate to severe & severe CDAI respectively. The Pearson correlation coefficient between IBUS-SAS & CDAI was 0.7 (95% CI 0.62-0.77; p < 0.001). The IBUS-SAS in patients with normal CRP levels (< 5mg/L) was 8 (± 19.54) & in patients with elevated CRP was 64 (± 18.99). The IBUS-SAS in patients with normal FC was 8 (± 19.65) & elevated FC (>250mcg/g) was 64.5 (± 22.66). The Pearson correlation coefficient between IBUS-SAS & CRP was 0.49(95% CI 0.37-0.60; p < 0.001) and with FC was 0.58 (95% CI 0.46-0.68; p < 0.001). The IBUS-SAS correlated well with SES-CD score with IBUS SAS scores of 8 (± 12.92), 53.5 (± 16.35), 65 (± 20.83) & 65 (± 8.62) in patients with inactive, mild, moderate, & severe SES-CD respectively. The Pearson correlation coefficient between IBUS-SAS & SES-CD was 0.77 (95% CI 0.7-0.82; p < 0.001). The IBUS-SAS score of > 37.5 revealed an area under the curve of 0.96 (95% CI 0.92 – 0.99) with a sensitivity of 94% & specificity of 91% to predict endoscopic disease activity (SES-CD > 3). Conclusion The IBUS-SAS score correlated very well with clinical and endoscopic disease activity as well as biomarkers. A score > 37.5 had a sensitivity of 94% and specificity of 91% to predict the presence of endoscopic disease activity.