Children with atopic dermatitis (AD) are more likely than children without AD to react to a patch test and should be referred to a specialist for evaluation.
Children with atopic dermatitis (AD) are more likely to react to at least 1 allergen on patch testing compared with children without AD. The findings, published in Journal of the American Academy of Dermatology, highlight the importance of referring children with AD to be referred to a specialist for evaluation of allergic contact dermatitis (ACD).
ACD is a is caused by a type 4 hypersensitivity reaction, while 80% of patients with AD also have type 2 inflammation occurring in their bodies. While it was previously thought ACD and AD could not co-occur because one was type 4 and the other type 2, new research shows the situation is not so simple.
Patch testing is the current gold standard to diagnosis ACD, but less than 10% of it is performed on children.
“AD affects over 20% of children compared to less than 10% of adults. As ACD cases in children may be misconstrued to be AD, patch testing is often not performed, resulting in the underdiagnosis of ACD.
In this study, the researchers conducted a retrospective case-control study evaluating the prevalence of ACD in both children with and without AD. A total of 912 children were included (615 with AD and 297 without AD). In both groups, the majority were female (61%). The mean age for being patch tested was 11 years for the AD group and 12 years for the no AD group. The majority of patients were White (62% AD group vs 74% no AD group).
Patients with AD were more likely to have other conditions in the “atopic triad”: 32% of patients with AD had allergic rhinitis compared with 20% of patients without AD and 25% of patients with AD had asthma compared with 10% without AD.
The researchers found children with AD saw more providers (2.3 on average) compared with children without AD (2.1 on average). Duration of dermatitis prior to being referred for patch testing was 4.1 years for the AD group compared with 1.6 years for the no AD group. The researchers surmised the longer time for patients with AD may be the result of ACD looking similar to AD.
Despite the number of allergens tested per patient and the testing series chosen being similar across the groups, patients with AD were more likely to have more than 1 positive reaction and a greater number of positive results, overall.
The most common allergen for both groups was nickel (16% AD group vs 14% no AD group). Cobalt, fragrances, preservatives and the antibiotic neomycin were all in the top 10 allergens for both groups. Both nickel and cobalt are found in costume jewelry, toys, keys and metal accessories.
The top 10 weren’t completely the same, however. Allergens that were missing from the no AD group but were present in the top 10 for AD group were cocamidopropyl betaine (9%), formaldehyde (8%) and Amerchol L101 (6%). Among the top 10 for the no AD group, but not the AD group, were propolis (8%) and hydroperoxides of limonene (5%).
The authors conjectured that the reason children with AD may be more likely to have more than 1 positive reaction and more overall results for patch testing was because these individuals are exposed more than children without AD to topical treatments, such as moisturizers, skin cleansers and topical medicaments.
They listed some limitations to the study, such as the multicenter nature, which may result in technical variabilities affecting the outcome of patch testing. In addition, irritant reactions could be incorrectly interpreted as positive reactions, while false negative reactions are also possible.
“The results of this study underscore the need for children with AD to be referred to a specialist for evaluation of ACD,” the authors concluded. “Uncovering potentially relevant contact allergens can lead to improvement in quality of life, can decrease use of topical steroids and systemic immunosuppressants, and can significantly lessen overall disease severity.”