Accurate endoscopic assessment of mucosal inflammation is critical in managing Ulcerative Colitis (UC). Mayo endoscopic score (MES) and Ulcerative Colitis Endoscopic Index of Severity (UCEIS) have significant interobserver variability. The role of Linked Color Imaging (LCI) in assessing inflammation is uncertain. We aimed to assess the reliability of LCI in UC.

A multi-centre international survey-based study was designed with 20 sets of high-definition white light (HDWLE) images or videos matched with LCI. Each set had varying severities of inflammation as determined by Nancy and Picasso histopathology scores. The MES and UCEIS were rated along with confidence level (high vs low). To assess interobserver variability, we used percentage agreement and Kappa score with 95% confidence intervals stratified by imaging modality and scoring system. A mixed logistic regression model was constructed to assess accuracy.

43 gastroenterologists from 4 centres were included. 26 (59.1%) were experts and 11 (25.6%) had prior LCI experience. Interobserver variability was moderate overall with percentage agreement between 62-70% and Kappa scores between 0.48-0.56. There was no difference in interobserver variability between HDWLE and LCI. Agreement was slightly higher for UCEIS than MES (Table 1). 73% reported high confidence prediction with confidence decreasing with increase in histological severity. Participants rated severity accurately 66% of the time using MES with accuracy decreasing with increase in histological severity. Accuracy was higher for participants with prior LCI experience. Results for UCEIS were inferior with accuracy at 58% overall. There was no evidence of a difference in accuracy between the two imaging modalities irrespective of the index used for scoring.

Table 1: Interobserver variability results

*95% confidence interval

Interobserver variability remains a challenge in accurately assessing inflammation in UC despite advances in technology and validated scoring systems. Our study suggests that LCI achieves moderate interobserver agreement with accuracy of 66% and is not superior to HDWLE.