Inter-rater Reliability and Accuracy of NBI Score for Activity Evaluation in Ulcerative Colitis

Colonoscopy is a critical tool for the management of Ulcerative Colitis (UC). In this study, we aim to explore the accuracy of Virtual Chromoendoscopy (VCE) using Narrow Banding Imaging (NBI), and magnification using Near Focus (NF) for a better definition of endoscopic inflammation grade in UC patients compared to standard white light (WL) endoscopy alone.

This is a non-randomized prospective study including all the patients who underwent a colonoscopy (for any reason) between April and September 2023 (with protocol number n. 60/2019.20). During the endoscopic evaluation, at least one image with white light - evaluated using the Mayo Endoscopic Score (MES), one image with NBI, one image with NBI plus NF, and a biopsy were obtained in each colonic tract (cecum, ascending colon, transverse colon, descending colon, sigmoid colon, and rectum). All the stored images were evaluated by three endoscopists separately and compared with the results of the histological evaluation.

A total of 31 UC patients were included. The inter-rater reliability concerning the different scores used (MES, NBI score, and NBI plus NF score), which was evaluated with Cohen's kappa coefficient, was good for the MES, good to excellent for the NBI score, and good for the NBI plus NF score. The concordance between histological evaluation (using the Nancy Index) and the MES was unsatisfactory for all the endoscopists, while the concordance between the NBI evaluation score and the Nancy Index was good to excellent.

The results in the present study suggest that the new endoscopic technologies could be useful to better define disease activity in IBD patients driving better therapeutic strategy.