Background: Atopic dermatitis (AD) is the most common chronic inflammatory skin disease in childhood. Few data are available about AD phenotypes and their nationwide distribution.
Methods: We performed a cross-sectional multicenter study involving some of the main Italian pediatric allergy centers from 9 Italian cities. A structured questionnaire was administered to 371 children with AD. Patients were divided in 2 groups: preschool children (aged ≤5 years) and schoolchildren (aged 6-14 years). A latent class analysis was used to detect AD phenotypes and to investigate their association with risk factors and other atopic diseases.
Results: Latent class analysis identified 5 AD phenotypes in preschoolers (“moderate-severe AD, high comorbidity”, 8%; “moderatesevere AD, low comorbidity”, 35%; “mild AD, low comorbidity”, 20%; “mild AD, respiratory comorbidity”, 32%; “mild AD, food-induced comorbidity”, 5%) and 4 AD phenotypes in schoolchildren (“moderate-severe AD, high comorbidity”, 24%; “moderate-severe AD, low comorbidity”, 10%; “mild AD, low comorbidity”, 16%; “mild AD, respiratory comorbidity”, 49%). Parental history of asthma and eczema, early day-care attendance, and exposure to molds were significantly associated with the “moderate-severe AD, high comorbidity” phenotype in preschool children (P<.05). The “moderate-severe AD” phenotypes were also associated with the highest burden in terms of medication use and limitations in daily activities.
Conclusions: The detection of different AD phenotypes highlights the need for a stratified approach to the management of this complex disease and for further studies to predict the course of AD and to develop more efficient therapeutic strategies.

Key words: Atopic dermatitis, Epidemiology, Pediatrics, Quality of life, Environment and hygiene hypothesis