Atopic dermatitis and risk of autoimmune conditions: Population-based cohort study

Background: Atopic dermatitis (AD) is associated with immune dysregulation, but epidemiologic data on the pattern of autoimmune comorbidity in people with AD are limited. Objective: We sought to determine the risk of autoimmune conditions in people newly diagnosed with AD. Methods: Retrospective cohort analysis (January 2009 to December 2018), using the UK-based Oxford-Royal College of General Practitioners Research and Surveillance Centre primary care database. We compared baseline prevalence and incidence after diagnosis of autoimmune conditions in 173,709 children and adults with new-onset AD and 694,836 age-, sex-, and general practitioner practice-matched controls. Outcomes were a composite of any autoimmune condition (Crohn disease, ulcerative colitis, celiac disease, pernicious anemia, type 1 diabetes, autoimmune hypothyroidism, Graves disease, psoriatic arthritis, rheumatoid arthritis, ankylosing spondylitis, systemic lupus erythematosus, Sjogren syndrome, vitiligo, alopecia areata, and multiple sclerosis) and each individual autoimmune condition. Results: Preexisting autoimmune conditions were more common in people diagnosed with AD compared to controls (composite 5.8% vs 4.3%). Excluding people with preexisting autoimmune disease, there was an association between AD and incidence of new-onset autoimmune disease (composite adjusted hazard ratio [aHR] 1.28; 95% confidence interval [CI] 1.23-1.34). Risk was highest for more severe AD (aHR 1.99; 95% CI 1.77-2.23) than moderate AD (aHR 1.33; 95% CI 1.19-1.49) or mild AD (aHR 1.22; 95% CI 1.16-1.28). People with AD were at significantly increased risk of developing psoriatic arthritis, Sjogren syndrome, Crohn disease, vitiligo, alopecia areata, pernicious anemia, ulcerative colitis, rheumatoid arthritis, and hypothyroidism (aHR range 1.17-2.06), but not other autoimmune conditions. Conclusion: People with AD have an increased risk of multiple autoimmune conditions, especially those with more severe AD.