Transabdominal intestinal ultrasound parameters as intermediate treatment targets in a treat-to-target strategy for moderate-to-severe ulcerative colitis

Background/Aims: This study aimed to investigate the prognostic value of early post-induction intestinal ultrasound (IUS) findings in predicting long-term clinical outcomes among patients with moderate-to-severe ulcerative colitis (UC). Methods: This retrospective, single-center study consecutively enrolled patients with moderate-to-severe, left-sided or extensive UC. Clinical endpoints were assessed at the end of follow-up or 1 year after induction therapy (for patients with at least 1 year of follow-up) and categorized as clinical remission (Short Clinical Colitis Activity Index SCCAI ≤ 2) or non-remission (SCCAI > 2). Patients who experienced a negative disease course before the evaluation point were classified as clinical non-remission. Results: A total of 56 patients were included. The bowel wall thickness (BWT; 5.1 ± 1.7 mm vs. 6.0 ±1.4 mm; P= 0.032) and Milan ultrasound criteria (MUC; 8.3 ± 3.2 vs. 9.9 ± 2.2; P= 0.029) evaluated at early follow-up IUS were lower for patients reaching longterm clinical remission. Patients with BWT < 5 mm on early follow-up IUS (83% vs. 45%; P= 0.006) or MUC < 6.2 (100% vs. 45%; P< 0.001) had a significantly higher rate of long-term clinical remission. Kaplan-Meier analysis revealed a lower cumulative probability of a negative disease course in patients with BWT < 5 mm (P= 0.025) or MUC < 6.2 (P= 0.025). Cox regression analysis identified BWT ≥ 5 mm as an independent predictor of a negative disease course. Conclusions: BWT <5 mm and MUC < 6.2 may serve as intermediate targets for IUS-guided "treat-to-target" strategy, offering a practical approach to improve longterm clinical remission in patients with moderate-to-severe UC.