Impact of Individual Colonic Segment Histological Activity on Disease Relapse in Patients with Ulcerative Colitis

<b>Background/Objectives</b>: The aim of this study was to assess the role of histological activity in individual segments of the colon in predicting disease relapse in patients with ulcerative colitis. <b>Methods</b>: This was a prospective observational study on patients with ulcerative colitis in clinical remission. Biopsies were taken of multiple segments of the colon, and histological activity was assessed using the Geboes (GB) score. Patients were monitored for disease relapse for 12 months. The primary objective was to determine the predictive value of histological activity of the individual segments of the colon on disease relapse. The secondary objective was to assess whether having multiple segments in histological remission is associated with disease relapse. <b>Results</b>: Of 253 patients, 19% had disease relapse. Histological activity (GB ≥ 3.1) was not predictive of disease relapse for the rectum (adjusted odds ratio [aOR] 0.95, confidence interval [CI] 0.46-1.98, <i>p</i> = 0.894), sigmoid (aOR 0.67, CI 0.24-1.90, <i>p</i> = 0.451), descending colon (aOR 1.52, CI 0.43-5.39, <i>p</i> = 0.519), transverse colon (aOR 0.47, CI 0.10-2.18, <i>p</i> = 0.332), and right colon (aOR 1.75 CI 0.73-4.18, <i>p</i> = 0.209). Histological remission (GB ≤ 2.0) was also not predictive of remaining in remission for any individual colonic segment nor was there any benefit of having multiple segments with histological remission compared to having ≤1 segment in histological remission (aOR 0.56, CI 0.28-1.10, <i>p</i> = 0.093). <b>Conclusions</b>: Histological activity in any individual colonic segment or the number of colonic segments with histological remission was not predictive of disease relapse.