P170 Can histological activity of ulcerative colitis be predicted by assessment of the rectosigmoid colon?

Abstract

Abstract Background Rectosigmoidoscopy is frequently used to assess disease activity in patients with ulcerative colitis (UC). Most recent guidelines suggest that the inflammatory activity of the whole colon can be inferred by endoscopic findings in the rectosigmoid colon. Nevertheless, whether the right colon can have endoscopic or histological activity when there is endoscopic and histological remission in the left colon, is yet to be completely determined. Aim To assess whether UC histological activity (HA) and improvement (HI) can be deduced by the findings in the rectosigmoid colon. Methods Retrospective single center cohort study. Consecutive patients with previously diagnosed UC undergoing endoscopic assessment, from January 2014 to September 2022, were included. Inclusion criteria were: a complete colonoscopy with adequate bowel preparation and biopsies made in all the four segments of the colon and in the rectum. Demographic, clinical, endoscopic (Mayo endoscopic subscore (MES)) and histological (Geboes score (GS)) data at the time of the colonoscopy was collected. Agreement and correlation between findings in the rectosigmoid and the whole colorectum were calculated with the kappa coefficient (k) and the Spearman correlation coefficient (r). Results Inclusion of 264 patients (49.2% male). Median age was 5015.7years. Smoking history in 33.5% of patients. Extension of UC was: proctitis in 13 (4.9%), left colitis in 109 (41.3%) and extensive colitis in 142 (53.8%) patients. MES was 0 in 139 (53.7%) patients, 1 in 52 (20.1%), 2 in 36 (13.9%) and 3 in 32 (12.3%). GS was 0 in 19 (7.3%), 1 in 124 (47.5%), 2 in 50 (19.1%), 3 in 40 (15.3%), 4 in 10 (3.8%) and 5 in 18 (6.9%). Regarding endoscopic activity, a very high correlation was found between MES of the whole colorectum and MES of the left colon (k=0.88, r=0.92). As far as HA (GS1.1) is concerned, HA in the whole colorectum was highly correlated with HA in the rectosigmoid colon (k=0.8, r=0.82), both in the whole cohort and in the subgroup of patients with extensive colitis (k=0.8, r=0.82). When assessing HI (GS<3.1) moderate coefficients (k=0.66, r=0.69) were found in the whole cohort. Patients with extensive colitis revealed similar agreement and correlation coefficients (k=0.69, r=0.71). Conclusion Endoscopic and histological activity in the rectosigmoid colon of patients with UC has a high correlation with activity in the whole colorectum. Therefore, UC activity can be inferred by analysis of the distal segments of disease. These findings reinforce that inflammatory activity in patients with UC can be assessed with rectosigmoidoscopy alone.