Recent insights into the epidemiology of atopic dermatitis
Atopic dermatitis (AD) has complex risk factors and effects on patients. AD patients experience itch, skin pain, sleep disturbances, and other symptoms that can profoundly impact their quality of life. Yet, little is known about the longitudinal epidemiology and burden of AD in children.
- Johansson et al 1 reported on the ongoing BAMSE cohort study. BAMSE followed 4089 individuals regularly from birth regarding AD and atopic diseases with surveys and clinical examinations; 3055 individuals were assessed at year 24 of follow-up. At 24 years, the 12-month prevalence of AD was 17.8% and more common in women than men (20.5% vs. 14.8%). The point prevalence of AD on clinical examination was 8.0%. These high prevalence estimates are consistent with multiple other recent studies in the United States and globally. 2-4 Prevalence measures a combination of both new-onset (incident) cases and persistence of childhood disease. Importantly, BAMSE found the proportion of adult-onset AD was 16.9%. These results are consistent with previous studies that found substantial rates of adult-onset AD. 5 Additionally, men were more likely to have AD in the first year of life, but less likely than women to have AD in adolescence and young adulthood.
- Paller et al 6 recently initiated PEDISTAT, an international, longitudinal 5-year registry of the disease course, comorbidities, treatment, and disease burden children age <12 years with moderate-severe AD. While the study is ongoing, the authors reported the baseline characteristics of the registry. They found that most of the enrolled children were not treated with a systemic therapy, had inadequately controlled disease and a high disease burden. These results emphasize the need for very safe and highly effective systemic therapies for moderate-severe AD in children.
I look forward to seeing the results of these ongoing study and how they will inform our understanding of the epidemiology and comorbidities of AD.
Numerous risk factors for AD have been examined. Infections have been explored as a potential risk factor for AD for more than 30 years.
- Lin et al 7 conducted a population-based, nationwide case-control study including 5,454 children with AD matched with 16,362 healthy controls without AD. They found that prior to AD diagnosis, all infections including skin infection up to 2 years of age were more frequent in children who subsequently developed AD compared to healthy controls.
- Medeleanu et al 8 reported findings from the Canadian Healthy Infant Longitudinal Development (CHILD) Cohort Study, which included a longitudinal birth cohort of 3,272 parents and infants recruited during pregnancy. They found that infants with moderate-severe vs. no or mild lower respiratory tract infections in the first 18 months of life had significantly higher rates of AD and type 1 allergen polysensitization at age 3 and 5 years. These associations remained significant after adjusting for sex, breastfeeding duration, and parental history of atopy or asthma.
Together, these studies suggest that prevention and expedient treatment of early life infections may lower risk for AD in childhood. Conversely, children at risk for AD who experience certain infections early in life may benefit from increased surveillance for AD and atopic disease.