O4 Multicentre prospective validation study of the paddington international virtual chromoendoscopy score (PICaSSO) in ulcerative colitis

Introduction Mucosal healing (MH)is an important goal in the treatment of ulcerative colitis (UC). The newly published PICaSSO score characterises subtle mucosal and vascular changes and defines MH. We aimed to validate in real-life the PICaSSO score and assess its ability to predict relapse. Methods Patients with UC were prospectively recruited from 11 international centres. Participating endoscopists experienced in IBD received training on PICaSSO before starting the study. The rectum and sigmoid were examined using iScan 1,2&3 (Pentax, Japan) and inflammatory activity was assessed using Mayo, UCEIS and PICaSSO. Biopsies were taken for histological assessment using Robarts Histological Index (RHI), Nancy, ECAP, Geboes and Villanacci. Follow up data was obtained at 12 months. Results A total of 307 patients were recruited.The interobserver agreement for the PICaSSO score was 0.879 (95% CI 0.826–0.924). The PICaSSO total and PICaSSO mucosal scores strongly correlated with histology scores and was statistically better than MES and UCEIS as show in figure 1. When using a PICaSSO total score of ≤3 the AUROC to predict MH by RHI (≤3 + absence of neutrophils) was 0.90 (95% CI 0.86–0.94) and when we compare the AUROC of Picasso vs Mayo p was =0.06. When using the Nancy score (≤1) the AUROC was 0.816 (95% CI 0.77–0.87). A Kaplan-Meier curve shows a significant favourable survival probability without relapse with a PICASSO score of ≤3 Likelihood ratio test=26.41, p Conclusions This real-life validation study shows the electronic chromoendoscopy score, PICaSSO, can predict accurately histological healing and long-term remission and can be a useful tool in the management of UC.