Chronic conditions associated with paediatric onset inflammatory bowel diseases: A population‐based study

Objective Several conditions are associated with inflammatory bowel disease (IBD), including immune‐mediated inflammatory diseases (IMIDs), extraintestinal manifestations (EIMs), and psychiatric disorders. This study aimed to describe at population‐level the comorbidities and their relative burden in paediatric‐onset IBD (pIBD). Methods All patients diagnosed with Crohn's disease (CD) or ulcerative colitis (UC) before age 17 between 1988 and 2011 and recorded in the EPIMAD population‐based registry were retrospectively followed until 2013. Comorbidities included chronic diseases, obesity (defined as a body mass index [BMI] z ‐score >1.645), and underweight (defined as a BMI z ‐score <−2), conditions requiring hospitalisation, serious infections, pneumopathy, meningitis, pyelonephritis, IMID, and EIM. Results A total of 1344 patients were included (1007 CD, 337 UC), with a median age at diagnosis of 14.3 years (interquartile range 11.7–16.0). Over a median follow‐up of 8.3 years (4.3–13.9), 15.8% developed at least one EIM, 9.3% at least one IMID, 12.7% developed dermatological conditions, and 5.1% serious infections; 18.4% were classified as underweight and 8.5% as obese. Younger age at diagnosis (<14 years) and more extensive disease were associated with an increased risk of EIM and underweight, while CD was independently associated with underweight (hazard ratio, 3.3; 95% confidence interval, 2.0–5.0). Patients with dermatological conditions or IMID were more frequently treated with biologic therapies. The incidence of obesity, IMID and dermatological conditions increased across the study period. Conclusions In this population‐based pIBD cohort, the most common conditions were underweight, IMID, dermatological diseases, EIM and obesity.