Transmural healing in ulcerative colitis patients improves long-term outcomes compared to endoscopic healing alone.

Background & aims: Endoscopic healing (EH) is recognized as a long-term treatment goal for patients with ulcerative colitis (UC). We investigated whether transmural healing (TH) in UC as assessed by intestinal ultrasound (IUS) is associated with improved outcomes compared to EH alone.

Methods: We performed a retrospective study in a tertiary center on patients with left-sided or extensive UC on stable maintenance treatment who had EH [Mayo Endoscopic Subscore (MES) ≤1) and an IUS performed within 6 months of an endoscopy with no treatment alterations between IUS and endoscopy. TH was defined as bowel wall thickness (BWT) <3 mm. The primary outcome was relapse-free survival in patients with and without TH.

Results: A total of 61 patients (MES 0: 44.3%; MES 1: 55.7%) with a median follow-up of 20 months were included. On IUS, 72% of patients had TH. Twenty-three patients had a relapse (first-year relapse risk: TH: 7.5% vs no TH: 29.4%, P = .004; MES 0: 3.7% vs MES 1: 20.8%, P = .059). In multivariate Cox regression, female gender [hazard ratio (HR), 2.63; 95% CI 1.05-6.58; P = .039], two or more previous advance therapies (HR, 4.06; 95% CI 1.08-15.28; P = 0.038), and non-TH (HR, 3.99; 95% CI 1.31-12.20; P = .015) were associated with a relapse whereas EH level (MES 0 vs MES 1) was not an associated factor (HR, 1.06; 95% CI 0.32-3.55; P = .924).

Conclusions: In UC patients TH is associated with lower relapse risk compared to EH alone. These findings imply that IUS is a non-invasive, low-cost alternative to endoscopy for stratifying UC patients for risk of relapse.