Background Associations between inflammatory bowel diseases (IBDs) and other immune-mediated diseases have been described in adult populations. Whether such associations exist in childhood-onset disease remains unknown.

Objectives The authors sought to evaluate whether paediatric IBD is associated with the occurrence of other immune-mediated diseases.

Study design The authors identified cases of Crohn's disease (CD) and ulcerative colitis (UC), ≤20 years of age, using administrative data from 87 health plans. Each case was matched to three controls, on the basis of age, gender, and geographical region. The authors used logistic regression to compare the prevalence of various immune-mediated diseases (identified by International Classification of Diseases, ninth revision codes) in cases versus controls.

Results The study included 737 children with CD (1997 controls) and 488 with UC (1310 controls). CD was associated with a higher prevalence of rheumatoid arthritis (OR 15.7, 95% CI 4.6 to 53.7), lupus (OR 41.0, 95% CI 2.3 to 719.1) and hypothyroidism (OR 2.9, 95% CI 1.4 to 6.1), with a trend toward an increased prevalence of asthma, eczema, allergic rhinitis and diabetes. UC was associated with a higher prevalence of diabetes (OR 2.7, 95% CI 1.1 to 6.6), with a trend towards increased prevalence of asthma, eczema, allergic rhinitis, hypothyroidism, rheumatoid arthritis and lupus.

Discussion Children with IBD, particularly CD, have an elevated risk for immune-mediated conditions. This comorbidity adds to the burden of paediatric IBD, and suggests common aetiologic mechanisms.