44 Factors associated with Fistulizing Crohn’s disease in children at diagnosis: A cross-sectional cohort study

Abstract Background Perianal manifestations are common at diagnosis of Crohn’s Disease (CD) in paediatric patients, occurring in approximately 25% of children with CD. Perineal Crohn’s disease (PCD) includes perianal fistulas, abscesses, fissures, and inflammatory anal skin tags. Perianal fistulizing Crohn’s disease (PFCD) is a form of PCD in which patients present with perianal fistulas and/or abscesses and it often dictates a poor prognosis in children. Studies demonstrate that PFCD is associated with more complications and increased severity over the course of the disease. Thus, early identification of PFCD is crucial in children with CD to adjust treatment plans and intervene before symptoms worsen. However, predictive factors of PFCD in children remain poorly understood, and no preventative measures have been established. Objectives This study’s primary aim was to investigate the factors associated with PFCD at paediatric CD diagnosis. Its secondary aims were to assess factors associated with PFCD’s severity with the Van Assche score (VAS), characterize the prevalence of PCD/PFCD in a Canadian cohort, and evaluate PCD management at diagnosis. Design/Methods In this cross-sectional single-center study, data was collected from paediatric patients (4-18 years old) diagnosed with CD between 2009 and 2021 at a single IBD center, with all patients undergoing a perineal magnetic resonance imaging (MRI) within 3 months of CD diagnosis. PCD was assessed clinically, endoscopically and through MRI results that rated perianal disease severity using the Van Assche Score (VAS) ranging from 0 to 22. With the data obtained from clinical charts, multivariate analyses were conducted to evaluate the association between clinical, laboratory, endoscopic and histological factors and PFCD and its severity. Results A total of 489 patients were included in the study (57.9% males; median age 13.8 years (interquartile range (IQR)=11.4-15.5), of which 229 (46.8%) had PCD. PFCD was identified with MRI in 115 patients (23.5%), with 13.9% (16/115) showing no clinical perineal manifestations at diagnosis of CD. The median VAS for patients with PFCD was 13.0 (IQR)=(9.0-15.0) as compared to 2.0 (IQR)=(0.0-2.0) in patients without PFCD (p0.0001). Male sex (OR=3.04 1.37-6.74), the presence of granulomas on intestinal biopsies (OR=3.30 1.54-7.08) and anal fissures (OR=5.69 2.13-15.18) at diagnosis were factors associated with PFCD and a higher VAS. Conclusion This study highlights the importance of early perianal MRI at CD diagnosis as occult PFCD may be discovered. Male sex, the presence of granulomas on intestinal biopsies and anal fissures at diagnosis were associated with PFCD and more severe PCD in paediatric patients.