P421 Correlation of bowel activity parameters in intestinal ultrasound to drug retention and trough drug levels in Crohn’s disease

Abstract

Abstract Background Introduction: Intestinal ultrasound can be used to assess transmural healing and response in Inflammatory bowel disease (IBD). Bowel wall thickness (BWT) appears to be the most applicable parameter for defining inflammation. Other parameters include amplified color Doppler signal, disappearance of the normal bowel wall layers and proliferation of mesenteric fat. The implication of incorporating these parameters in defining transmural healing and response is not clear. Our aim was to examine the significance of combining these parameters with BWT for defining transmural healing and response. Methods: Methods A post-hoc analysis of data from, 2 trials was used to examine the correlation of the different IUS parameters on drug retention and trough drug levels. Results: Results The study cohort included, 94 patients (median age, 24.5) with Crohn’s disease., 44 patients were treated with adalimumab (ADA) and, 50 with infliximab (IFX). There was a significant correlation of failure of drug retention and terminal ileum (TI) BWT >, 3 mm (P=0.07), amplified doppler sign (p<0.001), abnormal bowel wall stratification (p=0.005) and fat hypertrophy (p=0.001). This correlation remained significant when adding any other single abnormal parameter to the BWT (p<0.001), 2 abnormal parameters (p<0.001) or, 3 abnormal parameters (p=0.003). There was also a significant correlation between sufficient trough drug levels (ADA>7.1, IFX>5) and terminal ileum BWT <, 3 mm (P<0.001). However, there was no significant correlation between sufficient trough drug levels and the other ultrasonographic parameters and no significant correlation when combining any other ultrasonographic variables with the BWT. Conclusion Conclusions: Increased BWT was correlated with failure of drug retention. The addition of other ultrasonographic activity parameters did not significantly improve the predictive model. Therefore, TI-BWT should be used as the main target in the definition of transmural healing and response.