Experts Explore Disparities in Atopic Dermatitis

Differences in atopic dermatitis extend beyond the severity of the autoimmune disease, according to experts who presented during “Disparities in Atopic Dermatitis,” part of the afternoon session of the Thursday Dermatology Program at this year’s American College of Allergy, Asthma & Immunology Annual Scientific Meeting, being held November 4-8 live and virtually in New Orleans.

Age of presentation, skin color, and ethnicity all are areas in the AD continuum in which disparities are apparent. It’s important to recognize these differences, the experts agreed, because it can lead to better diagnosis, treatment, and outcomes.

The 2 speakers were Jonathan M. Spergel, MD, PHD, FACAAI, from the Perelman School of Medicine, University of Pennsylvania and Children’s Hospital of Philadelphia, who presented “How Atopic Dermatitis Differs Among Various Age Groups,” and Ama Alexis, MD, clinical assistant professor in the Department of Pediatrics at New York University’s Grossman School of Medicine, who presented “Ethnicity and Atopic Dermatitis: Differences, Similarities, and Gaps in Knowledge.”

Disparities by Age

“Many things do overlap,” Spergel stated, “but some things are more common in adults than children, and some things are more common in infants than in adults,” and these differences often can be broken down further.

Although what patients of any age have in common is that AD is a chronic and relapsing disease that can occur at any time, and is often characterized by scaly patches and plaques, principal differences exist in disease location. In infancy, the face and extensor surfaces (skin areas on the outside of joints) are the most common locations compared with childhood and beyond, when AD tends to occur more on flexural surfaces (skin areas on the insides of joints or where skin folds touch), the head and neck, and trunk.

Particularly important as well, Spergel said, is to pay attention to rare mimics, or diseases that closely resemble AD, when making a differential diagnosis, because these “are dramatically different in pediatric vs adult patients.” For example, immunodeficiencies and metabolic disorders are more common in children, whereas autoimmune conditions are more typical among adult patients.

When looking at natural history, marked differences exist in that most children who develop AD go on to develop true remission before adolescence, those who have early-resolving disease are usually male, and those with persistent disease typically have a family history of AD, late onset, or develop other forms of allergic contact dermatitis (ie, asthma, allergic rhinitis). In addition, immunoglobulin E sensitization occurs in less than 50% of children younger than 2 years vs more than 80% of older children and adults.

The principal difference in trigger factors is that food hypersensitivities happen more often in infancy and childhood but malassezia infection is typically concentrated in pubertal individuals and adults. And for immunology changes over time, whereas that in pediatric patients is chiefly driven by grater CLA-positive (CLA+) T helper (TH) 2 cell involvement, for adults, the immunologic response is more mixed, characterized by CLA+ TH2/TH22, elevated effector cells, and a CD8 population.

Disparities by Skin Color and Ethnicity

Alexis addressed several of the nuances in AD that are common among skin-of-color populations.

Using study results to illustrate epidemiological variations, Alexis noted how AD incidence and persistence are more common among non-Hispanic Black compared with non-Hispanic white children, even after adjusting for socioeconomic factors, and that African American children are 1.7 times more likely that White children to receive an AD diagnosis, again despite adjusting for confounders that include household income and having health insurance. In addition, vs Asian-Pacific Islanders and White, Blacks are 3 and 7 times more likely, respectively, to have AD diagnosed during an office visit. However, White patients still had the highest number of overall visits per capita.

Another study that evaluated children at 5, 9, and 15 years in 20 large US cities showed higher prevalences of AD among females vs males and Black and multiracial vs White children. Overall, transient disease was more common in White children vs persistent disease being more common among children with poorer overall health and higher odds of asthma history—again despite controlling for potential confounders, this time sociodemographics. In this same study, Hispanic children had a lower overall AD prevalence.

Disparities persist through the use health care resources that include ambulatory and emergency care, she continued. A study from 2019 showed that, accounting for “any level of disease control of AD, and this holds especially true for primary care visits and emergency department visits,” Black and Hispanic children were still 3 times more likely to be seen for AD than White children. In contrast, Black children with poor AD control still underutilized dermatologists. These findings were independent of sociodemographic factors and atopic comorbidities.

Genetic disparities when presenting for AD, and can principally be seen in loss of function mutations in the filaggrin (FLG) gene and TH cell involvement. Despite having a higher overall prevalence of AD, African American patients are 6 times less likely to have FLG loss-of-function mutations but more likely to have higher levels of TH17 cells in blood and lesional skin.

Lastly, she focused on clinical features differences, noting how skin-of-color patients have unique morphologies (follicular, psoriasiform, lichenoid) and different sequelae. On White patients, AD tends to present with a reddish color, and on patients with skin of color, AD is more likely to appear as a purple, gray, or brownish color. In addition, erythema can often be missed altogether or appear violaceous.