P229 Comparison of Different Histological Scoring Systems for Ulcerative Colitis [Nancy Histological Index, Robarts Histopathology Index and IBD-DCA (Inflammatory Bowel Disease-Distribution, Chronicity, Activity Score)] Among Specialists in GI Pathology and General Pathologists Pre- & Post Workshop

Abstract

Abstract Background Histopathology is an emerging treatment target and an important parameter in predicting clinical outcomes of patients with ulcerative colitis (UC). Histological scoring indices Nancy Histological Index (NHI) and Robarts Histopathology Index (RHI) have been developed and validated for UC. We aim to compare the inter-observer reliability of NHI, RHI and the recently described Inflammatory Bowel Disease-Distribution, Chronicity, Activity (IBD-DCA) Score among gastrointestinal (GI) pathologists versus general pathologists pre- and post-workshop to determine the scoring system with the best reproducibility. Methods Digital whole slide images of 20 H&E-stained biopsies of ulcerative colitis (UC) cases are scored independently by 6 GI pathologists and 44 general pathologists that attended the Singhealth GI Pathology Course 2023 using NHI, RHI and IBD-DCA on the digital Pathpresenter platform. The 44 course participants performed the scoring before the course and again after attending a 3-hour IBD workshop on the assessment of histological remission using these 3 scoring systems. Data tabulation using “Free Online Surveys” platform is collated and intraclass correlation coefficient (ICC) of each component of the scoring indices is calculated. The ICC values of <0.5, 0.5–0.75, 0.75–0.9, and >0.9, indicate ‘poor’, ‘moderate’, ‘good’, and ‘excellent’ agreement, respectively. Results There is good inter-observer reliability for IBD-DCA ‘Activity’ component (ICC 0.85) and NHI (ICC 0.83) among GI pathologists while lBD-DCA ‘Distribution’ component (ICC 0.395) has the poorest agreement. Poor to moderate inter-observer reliability for all 3 scoring systems (ICC 0.4 – 0.6) is seen among the 44 participants pre-workshop with an observed post-workshop improvement, achieving best agreement for the NHI, ‘lamina propria neutrophils’ component of RHI and IBD-DCA ‘activity’ component (ICC 0.7). Conclusion GI pathologists are generally consistent in assessing disease activity in UC with good inter-observer reliability for NHI (a scoring system with an emphasis on activity grade) and only the ‘activity’ component of the IBD-DCA. Our study confirms NHI as a reliable scoring system for UC with the best reproducibility and favour its application to assess histological response in routine clinical practice to help gastroenterologists better manage patients with UC. We have also demonstrated that improvement in NHI scoring reproducibility can be achieved after training workshop for pathologists less familiar with the application of IBD histological scoring.