OP35 Natural history of anal ulcerations in pediatric-onset Crohn’s Disease: A population-based study

International audienceBackgroundAnal ulcerations are frequently observed in Crohn’s disease (CD). Their natural history remains poorly known, especially in pediatric-onset CD. The aims of this study were: to determine in a population-based study the risk of anal ulcerations in pediatric onset CD; to identify risk factors for anal ulcerations; to evaluate the risk of progression towards suppurative lesions; to evaluate the risk factors of progression towards suppurative lesions.MethodsAll patients with a diagnosis of CD before the age of 17 years between 1988 and 2011 within the population-based registry EPIMAD were followed retrospectively until 2013. A specific collection of additional data was performed in patients with anal ulcerations at diagnosis or during follow-up. The variables collected included: proctological examination, diagnostic management (perineal MRI, endoscopic ultrasound, examination under general anaesthesia) and treatment (medical or surgical). Multivariate Cox models were used to identify factors associated with anal ulcerations and factors of progression towards suppurative lesions. An adjusted time-dependent Cox model was used to evaluate the risk of progression of anal ulcerations towards suppurative lesions.Results1005 patients were included (females, 450 (44.8%); median age at diagnosis 14.4 years (IQR, 12.0–16.1)). 257 (25.6%) had anal ulceration at diagnosis. Cumulative incidence of anal ulceration at 5 and 10 years from diagnosis was 38.4% (CI95%, 35.2–41.4) and 44.0% (CI95%, 40.5–47.2)