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Clinical Onset of Atopic Dermatitis
Rates of self-reported atopic dermatitis (AD) remain high after childhood, and adult-onset AD has different risk factor associations than childhood-onset AD. Researchers conducted a longitudinal study using data from 2 nationally representative community-based birth cohorts from the UK. Individuals were followed from birth through age 42-50 years. The primary outcome was the age period of self-reported AD symptom onset based on repeated measures of self-reported AD at each survey wave. Among the findings:
- The annual period prevalence of AD ranged from 5-15% in 2 cohorts over 17,000 participants.
- There was no clear trend in prevalence by age.
- Among adults reporting active AD during a given year, only 38% had symptom onset reported in childhood.
- Those with adult-onset disease were more likely to be women, of lower socio-economic group, smokers in adulthood, and less likely to have a history of asthma.
Abuabara K, et al. Clinical onset of atopic eczema: Results from two nationally representative British birth cohorts followed through mid-life. [Published online ahead of print June 28, 2019]. J Allergy Clin Immunol. doi: 10.1016/j.jaci.2019.05.040.
This survey included a large number of persons with eczema followed for up to 50 years, making it a very unique effort. Interestingly only about one third reported eczema as a child, which is much lower than expected. Possibly this is due to unusual genetic or environmental factors, but also suggests that not all the adults with "eczema" actually have atopic disease. Perhaps their eczema is non-specific endogenous eczema, allergic or irritant contact dermatitis or some other condition? This idea is reinforced by the data showing those with adult-onset disease were more likely to be women (perhaps suggesting ICD from home or work exposures), and less likely to have a history of asthma. Furthermore, "In a sub-analysis using data from the 1958 cohort only, genetic mutations previously associated with atopic eczema, including filaggrin null mutations, and allergen-specific IgE were more common among those with childhood-onset disease." We should always keep in mind that adult-onset atopic eczema does occur but that other forms of dermatitis are much more common in adults who do not have a history of childhood atopic disease. — Joseph Fowler, Jr., MD, Clinical Professor of Dermatology, University of Louisville, KY