Expert Roundtable: Comorbidities in Atopic Dermatitis

An estimated 7% of adults in the United States have atopic dermatitis (AD).¹ In addition to the disease burden and reduced quality of life associated with this condition, a range of research findings suggest a link between AD and various comorbidities. While the complex nature of this connection has not yet been elucidated, studies have shown elevated rates of high-risk behaviors — such as smoking, alcohol consumption, and reduced physical activity — in this patient population.^1,2

However, it is unknown whether AD severity is associated with a higher prevalence of comorbid health conditions. In a cross-sectional population-based study published in the Annals of Allergy, Asthma & Immunology in 2018, researchers sought to clarify this topic in a nationally representative sample of 8217 US adults who completed a structured questionnaire comprised of several patient-reported measures regarding AD severity and multiple comorbidities.¹

According to the results of analyses that controlled for sociodemographic factors, AD is associated with higher odds of having the following comorbid conditions compared with control patients:

• Asthma
• Hay fever
• Food allergy
• Anxiety and depression
• Autoimmune disease
• Obesity
• Diabetes
• High blood pressure
• Heart disease

While these associations were significant at all levels of AD severity, the strongest effect sizes were found for severe AD. Results further demonstrated “direct effects of moderate to severe AD on food allergy, anxiety and depression, and diabetes, direct and indirect effects on obesity, and indirect effects on high blood pressure and heart disease,” the authors wrote.¹ In sum, there is a “strong relation of AD severity to allergic, autoimmune, and cardiovascular comorbidities,” they concluded.

Dermatology Advisor interviewed the following experts for additional insights regarding comorbidities in AD: Joan Tamburro, DO, pediatric dermatologist at Cleveland Clinic, Ohio; Zelma Chiesa Fuxench, MD, MSCE, assistant professor of dermatology in the Perelman School of Medicine at the University of Pennsylvania; and Sonal Choudhary, MD, a dermatologist trained in dermatopathology and instructor at the University of Pittsburgh Medical Center, Pennsylvania.

Dermatology Advisor: What are some of the most common extracutaneous comorbidities in AD, and what are believed to be the underlying mechanisms linking these disorders?

Dr Tamburro: The most common extracutaneous comorbidities in AD are asthma, allergic rhinitis, and food allergies.³ Less common comorbidities include eosinophilic esophagitis/gastritis, truncal obesity and hypertension, and attention-deficit disorder/attention-deficit/hyperactivity disorder.^1,4 Associated health concerns include sleep abnormalities and psychosocial issues such as body image disturbance.

Dr Fuxench: There is increasing evidence suggesting that AD is more than a skin disease. AD has been frequently associated with other “atopic” diseases in the so-called atopic march, including higher rates of asthma, hay fever, and/or food allergies.³ Patients with AD — both adults and children — are also at higher risk for non-atopic comorbidities such as neuropsychiatric diseases, including higher rates of attention-deficit/hyperactivity disorder, depression, and suicidal ideation.

Lastly, systemic comorbidities that have been more recently associated with AD include cardiovascular disease, certain malignancies such as lymphoma and nonmelanoma skin cancer, and other autoimmune diseases such as alopecia or vitiligo.^1,5,6 However, recent studies have not shown an association with type 1 diabetes. It is unclear whether these associations are the result of  underlying inflammation in patients with AD, particularly those with more severe disease, that can promote an environment conducive to systemic inflammation or tumor formation in the case of malignancy.

Dr Choudhary: Studies done recently have noted significant associations between AD and multiple comorbidities, the most well-known ones being other atopic conditions such as hay fever and asthma. However, associations have also been noted between AD and certain noncutaneous chronic metabolic diseases such as diabetes and cardiovascular disease.

These connections may seem to depict some trends similar to those seen with psoriasis. In a study by Silverberg, et al, AD was associated with a significantly higher risk for asthma, hay fever, current obesity, 1-year history of food allergy, high blood pressure, diabetes, cardiovascular disease, autoimmune disease, anxiety/depression, and other chronic health conditions in bivariable models that were adjusted for sociodemographic characteristics.¹ This study also noted that younger age was significantly associated with asthma, food allergy, and anxiety/depression, while older age  was associated with high blood pressure, diabetes, cardiovascular disease, and other chronic conditions.