The association between atopic dermatitis and inflammatory bowel disease in adults: A cross-sectional study in a specialized atopic dermatitis clinic

Background: Atopic dermatitis (AD) and inflammatory bowel disease (IBD) share genetic susceptibility loci with immune regulation functions. Atopic dermatitis was associated with IBD mostly in database studies. Objective: To assess whether AD is associated with an increased prevalence of IBD in a tertiary dermatology clinic. Methods: A retrospective cross-sectional analysis using medical records of adults with verified AD followed up at an AD clinic, compared with age- and sex-matched (1:2) controls from the general dermatology clinic in the same hospital. Results: Overall, 9/364 (2.47%) of patients with AD had verified IBD, compared with 7/725 (0.97%) of controls (p = 0.0512). In multivariable logistic regression adjusting for age, gender and smoking, the association became significant (adjusted OR = 3.89, 95% CI: 1.28–11.85). Stratified for AD severity, only moderate-to-severe AD was associated with IBD (p = 0.035), with an adjusted OR of 4.45 (95% CI: 1.43–13.90). Mild AD was not associated with IBD, but the study was not powered for this sub-analysis. In the AD group, older age was associated with IBD (p = 0.0172). Conclusion: This study, in a robustly verified cohort of patients, supports an association between AD, especially the moderate-to-severe forms, and IBD. A multidisciplinary approach for patients with moderate-to-severe AD should extend to consider IBD.