Evaluation of the Risk of Relapse in Ulcerative Colitis According to the Degree of Mucosal Healing (Mayo 0 vs 1): A Longitudinal Cohort Study

Background and aims: Mucosal healing in ulcerative colitis (UC) has become a common endpoint in most clinical trials and a relevant therapeutic goal in clinical practice. Despite important differences between endoscopic Mayo scores 0 and 1, both scores are considered as mucosal healing in most important trials. The aim of the present study was to evaluate the risk of relapse in UC patients according to the degree of mucosal healing (endoscopic Mayo scores of 0 and 1). Methods: A prospective longitudinal cohort study was designed. All UC patients who presented with mucosal healing at colonoscopy were consecutively included. Mucosal healing was defined as an endoscopic Mayo score of 0 or 1. Clinical relapse was defined as the need for therapy to induce remission, any treatment escalation, hospitalization or colectomy. All clinical relapses were evaluated at months 6 and 12 after study entry. Results were subjected to unconditional stepwise logistic and Kaplan-Meier regression analysis. Results: One hundred and eighty-seven consecutive UC patients (126 [67.3%] with Mayo score 0 and 61 [32.7%] with Mayo score 1) were included. Of patients with Mayo scores 0 and 1, 9.4 and 36.6% respectively presented a relapse during the first 6 months of follow-up (p < 0.001). The only factor independently associated with UC relapses in the multivariate analysis was an endoscopic Mayo score of 1 (odds ratio 6.27, 95% confidence interval 2.73-14.40, p < 0.001). Conclusions: Patients with an endoscopic Mayo score of 1 have a higher risk of relapse than those with a score of 0. The concept of mucosal healing should be limited to patients with an endoscopic Mayo score of 0.