P331 Development of a novel transabdominal ultrasound disease activity score in patients with ulcerative colitis (UCUS score)

Abstract

Background: Ulcerative colitis (UC) occurs in young patients and is characterised by remitting and relapsing episodes. Evaluation of the colorectal mucosa with colonoscopy (CS) is the gold standard technique for determination of treatment. However, CS can be burdensome to both patients and physicians. Transabdominal ultrasonography (TAUS) may become an alternative to CS because it is non-invasive, is well accepted by patients, and has excellent spatial resolution. This study was performed to identify the US parameters that can predict UC endoscopic activity and develop a simple US score. Method(s): In total, 116 patients with UC underwent both TAUS and CS within a 1-week period. Three TAUS parameters were assessed: bowel wall thickness (BWT), bowel layer structure, and blood flow within the bowel wall using colour Doppler US. The wall structure was semi-quantitatively evaluated in terms of preservation, obscurity, or disappearance of the five-layer structure. Blood flow was semiquantitatively evaluated according to the Limberg score. Endoscopic activity was graded with the Mayo Endoscopic Score (MES) and UC Endoscopic Index of Severity (UCEIS). All assessments were performed for the sigmoid, descending, transverse, and ascending colon by advanced experts in a blinded fashion. Correlations between the US and CS variables were assessed using Spearman's rank correlation coefficient and receiver operating characteristic (ROC) analysis. Multiple regression analysis was employed to develop a predictive TAUS score for CS activity. Result(s): In total, 301 colon segments were retrospectively evaluated. BWT showed the strongest correlation with the MES and UCEIS (Spearman 0.767 and 0.771, p < 0.0001). The ROC curve showed that a BWT of < 0.0001] and that a BWT of >5 mm indicated high endoscopic severity (AUC, 0.86; p < 0.0001). The wall layer structure (Spearman 0.514 and 0.522, p < 0.0001) and colour Doppler findings (Spearman 0.767 and 0.771; p < 0.0001) were also correlated with the MES and UCEIS. Based on the multiple regression analysis results, we developed a US activity score as follows. BWT: 0 ( 3 mm, 5 mm); wall layer structure: 0 (preserved), 2 (obscure), and 4 points (disappearing); and colour Doppler: 0 (Limberg 0), 5 (Limberg 1), 10 (Limberg 2), and 15 points (Limberg 3). This novel US score of UC ("UCUS score") showed a strong correlation with the MES and UCEIS (Spearman 0.829 and 0.845, p < 0.0001). Conclusion(s): We developed a UCUS score that accurately identifies UC endoscopic activity. Non-invasive TAUS may be a very useful alternative to CS for quantitative evaluation of bowel activity.