S226 Poster presentations de-identifed CD cases. Cases with poor agreement were reviewed to clarify discrepancy and improve agreement. Phase 2: an additional 30 de-identifed CD cases blindly were reviewed by 12 independent expert readers. Inter-rater agreement was evaluated for all 4 key parameters. Statistics were performed using Stata 16. Bowel wall thickness (BWT) was assessed using intraclass correlation coeffcient (ICC) and the ordinal parameters using weighted Cohens Kappa. Results: The Delphi process reduced 12 activity parameters to 4 key contributors including BWT, color Doppler signal (CDI), infamma- tory fat and bowel wall echostratifcation (Figure 1). BWT was regarded as pathologic if the average of 4 measurements were > 3 mm for the small and large bowel, and grades of the add- itional parameters established (Table 1). Bowel wall thickness was comprised of 2 measurements in cross section and 2 in longitudinal orientation (Figure 2). Interobserver agreement was almost perfect for BWT: ICC=0.91 (95% CI 0.83 to 0.96) p = 0.001, while there was moderate agreement for CDI κ=0.60 (95% CI 0.48–0.72) p = 0.001. Agreement for infammatory fat detection was also moderate with κ= 0.50 (95% CI 0.33–0.66) p = 0.001, while stratifcation was fair κ= 0.39 (95% CI 0.26–0.53) p = 0.001. Conclusion: This expert consensus-based IUS activity score clearly establishes the reproducibility of this standardised approach to measure infammatory activity in patients with CD. Using our method, BWT which is known as the most important parameter, is highly reproducible with CDI and infammatory fat demonstrating moderate reproducibility. This score may provide the foundation for the future incorporation of IUS in research studies and clinical trials. P177 Lower vedolizumab trough levels before interval shortening are not predictive of success of the intervention B. Ungar* 1,2 , K. Malickova 3 , J. Hanžel 4 , M. Abu-Arisha 5 , S. Paul 6 , C. Rocha 7,8 , Z. Ben-Shatach 1,2 , O. Haj-Natour 1,2 , M. Yavzori 1,2 , E. Fudim 1,2 , O. Picard 1,2 , R. Eliakim 1,2 , U. Kopylov 1,2 , M. Lukas 3 , D. Drobne 4,9 , Y. Chowers 5 , X. Roblin 6 , F. Magro 7 , S. Ben-Horin 1,2 1 Sheba Medical Center Tel Hashomer, Gastroenterology Institute, Ramat gan, Israel, 2 Tel-Aviv University, Sackler School of Medicine, Tel Aviv, Israel, 3 ISCARE I.V.F. a.s ibd, IBD Clinical and Research Centre, Prague, Czech Republic, 4 University Medical Centre Ljubljana, Department of Gastroenterology, Ljubljana, Slovenia, 5 Rambam Health Care Campus, Bruce and Ruth Rappaport Faculty of Medicine, Haifa, Israel, 6 University Hospital of Saint- Etienne, Department of Hepatogastroenterology, Saint-Etienne, France, 7 University of Porto, Department of Biomedicine- Unit of Pharmacology and Therapeutics- Faculty of Medicine, Porto, Portugal, 8 University of Lisbon, Instituto de Saúde Ambiental- Faculty of Medicine, Lisbon, Portugal, 9 University of Ljubljana, Medical Faculty, Ljubljana, Slovenia Background: Pharmacokinetics of vedolizumab have been associ- ated with therapy outcome, although real-life data has been contra- dictory. Thus, we set to examine whether vedolizumab levels before therapy intensifcation may be associated with clinical, infammatory and endoscopic outcomes further on. Downloaded from https://academic.oup.com/ecco-jcc/article/14/Supplement_1/S226/5705209 by guest on 09 December 2023