Background: Endoscopic inflammation and healing are important therapeutic endpoints in ulcerative colitis (UC). We developed and validated a new electronic virtual chromoendoscopy (EVC) score which could reflect the full spectrum of mucosal and vascular changes including mucosal healing in UC.
Methods: Eight participants reviewed a 60-minute training module outlining the three different i-scan modes demonstrating the entire spectrum of inflammatory mucosal and vascular changes in UC. Performance characteristics in endoscopic scoring and predicting the histologic inflammation with EVC (iscan) by using 20 video clips before (pre-test) and after (post-test) were evaluated. Exploratory univariate factor analysis was performed on “PICaSSO” score covariates for mucosal and vascular score separately. Subsequently a proportional odds logistic regression model for the prediction of histological scores were analysed
Results: The inter-observer agreement for Mayo endoscopic score in the pre-test (k=0.85, 95% CI: 0.78–0.90) and the post test (k=0.85,95% CI: 0.77–0.90) evaluation were very good. This was also true for UCEIS in the pre and post-test score inter-observer agreement (k=0.86,95% CI: 0.77–0.92 and k=0.84, 95% 0.75–0.91). The inter-observer agreement of the PICaSSO endoscopic score was very good in the pre and post-test evaluations (k=0.92, 95% CI: 0.87–96; k=0.89, 95% CI: 0.84–0.94). The accuracy of the overall PICaSSO score in assessing histological abnormalities and inflammation by Harpaz score was 57% (95% CI: 48–65%), by RHI 72% (95% CI: 64–79%) and by ECAP (full spectrum of histologic changes) 83% (95% CI: 76–88%).
Conclusions: The EVC score “PICaSSO” showed very good inter-observer agreement. The new EVC score may be used to define the endoscopic findings of the mucosal and vascular healing in UC and reflected the full spectrum of histological changes.