Complete histologic normalisation is associated with reduced risk of relapse among patients with ulcerative colitis in complete endoscopic remission

Background: Clinical and endoscopic remission are treatment targets in ulcerative colitis (UC). The value of histologic healing in altering clinical outcomes among patients with complete endoscopic healing is not well established. Aim: To quantify the association between histologic activity and clinical relapse among patients with UC who were in complete endoscopic remission. Methods: This study included patients with UC from a prospective registry who were in complete endoscopic remission. Histologic activity was quantified by a senior gastrointestinal pathologist. Histologic activity was defined as lack of normalisation (Geboes score > 0) as well as histologically active disease (Geboes score ≥2.1 and ≥3.1). The primary outcome was clinical relapse within 2 years. Multivariable regression adjusting for potential confounders examined the independent predictive value of histologic changes. Results: The study included 83 patients (51% women) (median age 44 years; median disease duration 11 years). Forty-one (49%) had complete histologic normalisation. Within two years, 26 (31%) experienced clinical relapse. Patients with complete histologic normalisation were less likely to experience relapse (5/41, 12%) compared to those without normalisation (21/42, 50%, P < 0.001) (multivariable OR 7.22, 95% confidence interval (CI) 2.48-24.70) by the Geboes score. The individual components of the Geboes score predictive of relapse were architectural changes (P = 0.03) and increased chronic inflammatory infiltrate (P < 0.001). Conclusions: Complete histologic healing using the Geboes score was associated with reduced rates of clinical relapse among patients with UC in endoscopic remission.