Risk factors and long-term prognosis for colorectal strictures in ulcerative colitis.

Background: Strictures in ulcerative colitis (UC) are relatively uncommon but are associated with increased risk of malignancy and complications. Until recently, fibrogenesis and strictures have remained largely unexplored in UC.

Aim: To investigate the incidence, long-term prognosis and risk factors of colorectal strictures in a large cohort of UC patients.

Methods: A total of 938 hospitalized UC patients at Peking Union Medical College Hospital were included from 2014 to 2024. Stricture was defined as a fixed localized narrowing of the colorectal lumen. Risk factors for stricture formation were identified by multivariable Cox regression. Prognosis was analyzed using the Kaplan-Meier or Fine-Gray method. Sensitivity analysis excluded malignant strictures due to their distinct pathophysiology.

Results: The overall incidence of stricture was 12.4% over a median follow-up of 8.70 years, with a 10-year cumulative probability of 11.3%. Malignancy occurred in 8.6% of stricture cases. UC patients with strictures were at higher risk for intestinal complications, surgery and malignancy (P < 0.05). The 10-year cumulative probabilities of surgery and all-cause mortality were 37.6% and 1.6%, respectively. Age ≥ 40 years at diagnosis [hazard ratio (HR) = 2.197, 95% confidence interval (CI): 1.487-3.242] and extraintestinal manifestations (HR = 2.072, 95%CI: 1.326-3.239) were associated with higher stricture risk, while the use of biological agents such as vedolizumab (HR = 0.382, 95%CI: 0.203-0.720) was protective against strictures (P < 0.05). Sensitivity analysis on benign strictures showed consistent findings, with similar risk factors and worse long-term outcomes.

Conclusion: UC patients with strictures had worse long-term prognostic outcomes. Earlier endoscopic surveillance and biologic treatment should be considered in patients ≥ 40 years or those with extraintestinal manifestations.