Abstract and Introduction
Abstract
Background: Atopic dermatitis (AD) is a common chronic skin disorder and is well known to be associated with other atopic conditions. There is increasing evidence for an association also with nonatopic conditions, including autoimmune diseases, but data are limited about several autoimmune diagnoses.
Objectives: To investigate the association between AD and autoimmune diseases.
Methods: This case–control study used Swedish national healthcare registers. The source population comprised the entire Swedish population aged ≥ 15 years from 1968 to 2016. Cases, including all those with an inpatient diagnosis of AD (from 1968) and/or a specialist outpatient diagnosis of AD (from 2001), were matched by sex and age to healthy controls (104 832 cases of AD, 1 022 435 controls).
Results: AD was significantly associated with one or more autoimmune diseases compared with controls – adjusted odds ratio (aOR) 1·97, 95% confidence interval (CI) 1·93–2·01 – and this association was significantly stronger in the presence of multiple autoimmune diseases compared with only one. The association was strongest for autoimmune disorders involving the skin (aOR 3·10, 95% CI 3·02–3·18), the gastrointestinal tract (aOR 1·75, 95% CI 1·69–1·82) or connective tissue (aOR 1·50, 95% CI 1·42–1·58). In the overall analysis, men with AD had a stronger association with rheumatoid arthritis and coeliac disease than did women with AD. In subanalyses, the findings remained stable in multivariable analyses after adjustment for smoking and parental autoimmune disease.
Conclusions: This large population-based study indicates significant autoimmune comorbidity of adults with AD, especially between AD and autoimmune dermatological, gastrointestinal and rheumatological diseases. Having multiple autoimmune diseases resulted in a stronger association with AD than having only one autoimmune disease.
Introduction
Atopic dermatitis (AD) is one of the most common chronic skin disorders globally.[1] A recent systematic review, with data from all continents, found a 12-month prevalence of AD up to 17·1% among adults and 22·6% among children.[2] Essential features of AD are generalized dry skin, recurrent eczematous lesions and pruritus. Clinical symptoms can have a wide spectrum, with negative impact on health-related quality of life and work life, and having AD is a financial burden for the affected person as well as for society.[3–5]
AD is well known to be associated with other atopic conditions. There is increasing evidence for an association also with several nonatopic conditions, such as certain cancers, cardiovascular diseases, infections and neuropsychiatric disorders, although their relationships with AD are not fully understood.[6–8] Previous studies have also found an association between AD and several autoimmune conditions, including Crohn disease, ulcerative colitis, coeliac disease, alopecia areata and vitiligo.[9,10] A systematic review found that autoimmune diseases involving the skin and gastrointestinal tract were more frequent in individuals with AD, while conflicting results were seen for correlations with type 1 diabetes mellitus (DM1), autoimmune thyroiditis and rheumatoid arthritis (RA).[11] Increased knowledge within this field might lead to better monitoring of comorbidity and a deeper understanding of the disease burden and pathophysiology of AD. The aim of the present study was to explore the association between AD and a wide spectrum of autoimmune diseases in a large-scale, population-based study using Swedish national registers.