Disease course of ulcerative proctitis in children: A population-based study on behalf of the SIGENP IBD Group.

Background: The natural history of ulcerative proctitis (UP) has been poorly investigated in children.

Aims: We aimed to compare the disease course of children with UP at diagnosis to the other locations and to identify extension predictors.

Methods: This was a multicenter, observational study carried out from data prospectively entered in the SIGENP-IBD-Registry. Children with ulcerative colitis (UC) diagnosis and at least 1-year follow-up were included. On the basis of Paris classification UP patients were identified and compared with the other locations.

Results: 872 children were enrolled (median age at diagnosis: 11.2 years; M/F: 426/446), of whom 78 (9%) with UP. Kaplan-Meier analysis demonstrated increased cumulative probabilities of disease extension in the E1 group [1 year: 20.3%; 5 years: 52.7%; 10 years: 72.4%] compared to E3 group [1 year: 8.5%; 5 years: 24.9% and 10 years: 60.1%, p=0.001]. No differences were observed comparing E1 and E2 groups [p=0.4]. Cumulative probabilities of surgery at 1, 5 and 10 years were 1.3, 2.8 and 2.8% in the E1 group and 2.5, 8 and 12.8% in the E2-E3-E4 group, respectively (p=0.1). Cox regression analysis demonstrated that PUCAI>35 at diagnosis was associated with endoscopic extension (HR=4.9; CI 95% 1.5-15.2, p=0.006).

Conclusions: UP is associated with similar short and long-term outcomes compared to other locations.