Differences in disease characteristics and treatment exposures between paediatric and adult-onset inflammatory bowel disease using a registry-based cohort

Background: Previous studies highlighted a more extensive phenotype for paediatric-onset than adult-onset inflammatory bowel disease (IBD). However, most lacked long-term follow-up, and some were conducted before the era of biologics. Aims: The aim of this study is to compare disease characteristics and treatment exposures between paediatric-onset and adult-onset IBD. Methods: From a registry that periodically and uniformly retrieves demographics, disease characteristics/phenotype, and treatments, we compared the characteristics of paediatric-onset (diagnosed at ≥6 and <18 years) and adult-onset IBD, diagnosed during 2000–2022 and with ≥12 months follow-up. Results: Of the 2837 patients with Crohn's disease and 1332 with ulcerative colitis, 3316 had adult-onset and 853 paediatric-onset IBD. The median follow-up was 6 years. Patients with paediatric-onset presented with more extensive disease and received more intensified therapies, including biologics and JAK inhibitors than those with adult-onset IBD. Paediatric-onset ulcerative colitis showed a higher prevalence of E3 extensive colitis including pancolitis and a greater requirement for systemic steroids, immunomodulators, and biologics than adult-onset ulcerative colitis. Paediatric-onset versus adult-onset Crohn's disease exhibited greater L3 ileocolonic involvement and perianal disease phenotype, and higher exposure to immunomodulators and biologics. Kaplan–Meier curve and Cox proportional hazards analyses showed significantly lower 15-year biologic-free survival from diagnosis among those with paediatric-onset IBD than with adult-onset IBD (p = <0.001), indicating greater and earlier use of biologics in the former. Conclusions: Paediatric-onset presents with more extensive disease with higher exposures to immunomodulators and biologic therapies than adult-onset IBD.