Acute histological inflammatory activity is associated with clinical relapse in patients with ulcerative colitis in clinical and endoscopic remission

Abstract Background It has been suggested that acute histological activity has a prognostic value in the outcome of ulcerative colitis (UC) patients in clinical and endoscopic remission. Our aim was to assess the role of histology as a risk factor for clinical relapse (CR) in patients in both clinical and endoscopic remission. Methods Patients with left-sided or extensive UC in clinical and endoscopic remission (Mayo endoscopic subscore ≤1) undergoing colonoscopy for dysplasia surveillance with random colonic biopsies between 2005–2015 were included. Basal plasmacytosis, acute (AHA), and the chronic (CHA) histological inflammatory activity of all biopsy sets were evaluated. Results One hundred and thirteen patients were included. Median time in clinical remission at inclusion was 27 months (IQR 15–56). Eight percent of patients relapsed within the first year and 33% during the whole follow-up period. In the univariate analysis, the presence of AHA, alone (P = 0.048) or together with a past flare within the previous 12 months (P = 0.01), was associated with CR within the first year of follow-up. In the multivariate analysis, AHA, together with a flare within the previous 12 months, remained the only risk factor for relapse (RR = 7.5; IC95%; 1.8–29.9; P = 0.005). Conclusions In UC patients in clinical and endoscopic remission, the presence of AHA is a risk factor for clinical relapse.