Primary findings
In this longitudinal birth cohort study of 368 high-risk children, we found that increasing severity of early-onset AD was associated with sensitization to aeroallergens and allergic rhinitis at 6-7 and 12 years, while severity of late-onset AD after age 1 year was not. These findings suggest that aeroallergens penetrate the skin inflamed from AD in infancy more so than later and that an early-onset vs. late-onset debut represent different endotypes of AD that differentially associate with subsequent risk of respiratory allergy in childhood.