Development of atopic dermatitis in the DARC birth cohort.

The aim was to describe the relapsing pattern, sensitization and prognosis of atopic dermatitis (AD) in the first 6 yr in a population-based, prospective birth cohort. The DARC cohort includes 562 children with clinical examinations, specific-IgE and skin prick test at all follow-ups. All children were examined for the development of AD using Hanifin-Rajka criteria and for food hypersensitivity by oral challenges. Severity of AD was measured by objective SCORing Atopic Dermatitis (SCORAD). Point-prevalence of AD peaked at 18 months of age (10%) and decreased at 36 and 72 months to slightly below 7%. The 6-yr cumulative incidence was 22.8% and sensitization was found in 43% of children with AD. It was predominately sensitization to foods, however shifting toward inhalant allergens with age. Sensitization at >or=2 follow-ups affected severity, whereas short-term sensitization at one follow-up does not. Children with early, non-IgE mediated (intrinsic) AD outgrew more often their eczema; however if they develop persistent AD, they remain intrinsic. Early long-term sensitization worsens the prognosis, but 38% of all children have a debut later than 18 months of age. Boys had earlier onset of AD than girls. The large number of follow-ups gives a detailed picture of the relapsing pattern and shows that the relapses occur independently of time of onset. We could not establish any clear correlation between elimination diets and AD duration nor severity.