This retrospective study examines patients with ulcerative colitis who initiated advanced therapy for their disease. In clinical practice, patients with only mild inflammation on endoscopy (Mayo Endoscopic Subscore 1, or MES1) often do not undergo treatment optimization or therapy change. We stratified these patients based on histologic findings from biopsy samples and compared them with patients who had greater endoscopic activity (MES2). We evaluated long-term outcomes, including surgery and hospitalization, to determine whether current management strategies for patients with mild endoscopic disease should be reconsidered.

Inclusion Criteria:

• Confirmed diagnosis of UC (by routine clinical, radiographic, endoscopic and pathologic criteria);
• Patients starting a new advanced treatment for UC (either biologic agents or small molecules);
• Patients with endoscopic MES of 1 or 2 at the endoscopic reassessment (conducted after 12 ± 3 months following the initiation of advanced therapy)

Exclusion Criteria:

• Patients with unclassified colitis or Crohn's disease;
• Previous colonic surgery (eg. Pouch);
• Patients for whom biopsies were not obtained at the time of endoscopic reassessment (conducted after 12 months following the initiation of advanced therapy);

Adult patients diagnosed with ulcerative colitis who initiated advanced therapy between 2019 and 2025. Patients were stratified according to baseline Mayo Endoscopic Subscore (MES1 or MES2) and had available histologic assessment from endoscopic biopsies.