Natural History of Anal Strictures in Pediatric-Onset Crohn's Disease: Long-term Follow-up of a Population-Based Study.

Background: The risk and clinical course of anal stricture observed in Crohn's disease remains poorly known, particularly in pediatric-onset Crohn's disease.

Objective: To investigate the long-term clinical course of anal stricture in pediatric-onset CD using data from a population-based cohort.

Design: A retrospective observational study from a prospective population-based study.

Settings: Population-based study in Northern France.

Patients: All patients with a diagnosis of Crohn's disease before the age of 17 years between 1988 and 2011 within the population-based registry EPIMAD.

Main outcome measures: Primary outcome was the cumulative risk of anal stricture. Secondary outcomes included include risk of anal cancer, surgery, stoma and risk factors associated with anal stricture.

Results: A total of 1,007 patients were included (median age at diagnosis, 14.5 years; IQR, 12.0-16.1), median duration of follow-up 8.8 years (IQR, 4.6-14.2)). Among them one (0,1%) had an anal stricture at diagnosis and 26 (2.6%) during follow-up. From diagnosis, the 5- and 10-years cumulative incidence of anal stricture at was 0.6% (95% CI, 0.1-1.1) and 1.4% (95% CI, 0.5-2.3), respectively. Twenty-five (n = 25/27, 93%) patients had at least one episode of anal ulceration or fistulizing perineal Crohn's disease. In multivariable analysis, extraintestinal manifestations (HR 2.2, 95% CI, 1.0-4.8, p = 0.0270), colonic location (L2 vs L3 HR 1.2, 95% CI 0.6-2.7, p = 0.0064) and a history of fistulizing perineal Crohn's disease (HR 9.9, 95% CI, 4.3-22.8, p < 0.0001) were significantly associated with anal stricture. After a median follow-up of 6.2 years (2.4-10.6), 11 (41%) patients required at least one anal dilatation, and healing was observed in one patient. One patient (3.7%) had an anal cancer 7 years after stricture diagnosis, and 9 (33%) patients needed a stoma. Anal stricture was significantly associated with the need of stoma (HR 5.8, 95% CI, 2.3-14.3), p = 0.0002).

Limitations: It has a retrospective design which makes it prone to selection bias and residual confounding.

Conclusion: Within a population-based cohort of pediatric-onset Crohn's diease, the 10-year cumulative incidence of anal stricture was 1.4%, with associations identified with colonic disease location, and fistulizing perianal involvement. The presence of an anal stricture was linked to a fivefold increase in the likelihood of stoma formation. See Video Abstract.