Atopic Dermatitis in Early Childhood and Risk of Inflammatory Bowel Disease: A Scandinavian Birth Cohort Study.

OBJECTIVE: To examine the association between early-life atopic manifestations and later risk of inflammatory bowel disease (IBD), for which prospective data are scarce.

STUDY DESIGN: The population-based All Babies in Southeast Sweden (ABIS) and Norwegian Mother, Father, and Child (MoBa) cohorts follow children from birth (ABIS 1997-1999; MoBa 2000-2009) to the end of 2021. Based on validated questionnaires, parents prospectively reported information on asthma, food-related allergic symptoms, atopic dermatitis, and allergic rhinitis by age 3. IBD was defined by ≥2 diagnostic records in the national health registries. Cox regression estimated hazard ratios adjusted (aHR) for parental IBD, atopy, education level, smoking habits, and national origin. Cohort-specific estimates were pooled using a random-effects model.

RESULTS: We compiled data on 83,311 children (ABIS, n=9,041; MoBa, n=74,270). In over 1,174,756 person-years of follow-up, 301 participants were diagnosed with IBD. Children with atopic dermatitis at age 3 had an increased risk of IBD (pooled aHR=1.46 [95% confidence interval [CI]=1.13-1.88]), Crohn's disease (pooled aHR=1.53 [95%CI=1.04-2.26]), and ulcerative colitis (pooled aHR=1.78 [95%CI=1.15-2.75]). Conversely, any atopic manifestation by age 3 was not associated with IBD (pooled aHR=1.20 [95%CI=0.95-1.52]), nor were analyses specifically focused on early-life food-related allergic symptoms, asthma, and allergic rhinitis.

CONCLUSION: While atopic manifestations in early childhood were overall not associated with IBD, children with atopic dermatitis specifically were at increased risk of developing IBD, suggesting shared etiological traits; these findings might be useful in identifying at-risk individuals for IBD.