according to a published in the Journal of the American Academy of Dermatology.
Atopic dermatitis most commonly arises in infancy but also can emerge in later childhood and even adolescence, leading to a distinction between early- and late-onset disease, wrote Joy Wan, MD, of the University of Pennsylvania, Philadelphia, and coauthors.
“Early-onset, mid-onset, and late-onset AD appear to differ in the presence of active disease over time; however, whether these groups also differ in terms of the severity of AD is unknown,” they wrote.
In this observational cohort study, 8,015 individuals with childhood-onset atopic dermatitis – 53% of whom were female – were assessed twice-yearly for up to 10 years. Nearly three-quarters (72%) of the group had early-onset atopic dermatitis – defined as onset before 2 years of age – while 19% had mid-onset disease (3-7 years) and 9% had late-onset disease (8-17 years).
The study found that older age of onset was associated with better control, such that for each additional year of age at the onset of disease, there was a 7% reduction in the odds of poorer control of disease. Those who had mid-onset disease had a 29% lower odds of poorer control compared with those with early-onset, while those with late-onset disease had a 49% lower odds of poorer control.
The likelihood of atopic dermatitis persisting beyond childhood also appeared to be linked to the age of onset. Those with mid-onset disease had a 55% lower odds of persistent atopic dermatitis, compared with those with early-onset disease, while those with late-onset disease had an 81% lower odds.
“In all 3 groups, the proportion of subjects reporting persistent AD generally declined with older age, and the differences among the 3 onset age groups were most pronounced from early adolescence onward,” the authors wrote.
They noted that there was considerable research currently focused on identifying distinct atopic dermatitis phenotypes and endotypes, and their evidence on the different disease course for early-, mid-, and late-onset disease supported this idea of disease subtypes.
“However, additional research is needed to understand whether and how early-, mid-, and late-onset AD differ molecularly or immunologically, and whether they respond differentially to treatment,” they wrote. They also suggested that the timing of onset could help identify patients who were at greater risk of persistent or poorly controlled disease, and who benefits from more intensive monitoring or treatment.
The study was partly supported by the National Institute of Arthritis and Musculoskeletal and Skin Diseases and the Dermatology Foundation. Three authors declared funding, consultancies, or advisory board positions with the pharmaceutical sector. No other conflicts of interest were declared.