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.