Findings from a large study investigating the association between atopic dermatitis and autoimmune diseases

Linked Article:   Ivert et al. Br J Dermatol 2021; 185 :335–342. Atopic dermatitis (AD) is one of the most common chronic skin disorders globally and causes dry skin and recurrent itchy lesions. The proportion of people who have AD during a 1‐year period is about 17% among adults and 23% among children. Some studies have shown that AD is associated with autoimmune diseases. Autoimmune diseases occur when the body’s immune system attacks its own healthy cells and tissues. The aim of our study was to investigate the association between AD and autoimmune disease among Swedish patients aged 15 years or older. We used data from Swedish national healthcare registers and compared over 100,000 individuals diagnosed with AD with just over a million people from the healthy population who did not have AD. This is, to our knowledge, the largest study within this field. We found that adults with AD were more often diagnosed with autoimmune diseases compared with adults without AD. Autoimmune disorders involving the skin, the stomach or gut (such as Crohn disease, coeliac disease and ulcerative colitis), or the connective tissue (such as bones, tendons or ligaments) were most commonly associated with AD. In patients with more than one autoimmune disease, the association grew stronger with each additional disease. Greater awareness, screening and monitoring of autoimmune diseases can help ensure patients receive appropriate treatment and may also provide greater knowledge about AD. Further studies are needed, especially to identify patients with AD who are at higher risk for autoimmune diseases, and to explore if AD severity and treatment may affect the associations we found.