Development of atopic dermatitis in the DARC birth cohort Atopic dermatitis (AD) is a chronic, relapsing, itchy, inflammatory, skin disease, which usually appears in the first years of life. There is no gold- standard for the diagnosis of AD; it is based on clinical criteria combined with disease history, and the most common diagnostic tool is derived from Hanifin and Rajka in 1980 (1). The etiology of AD is complex, where epidermal barrier (2) and filaggrin defects (3) and two subsets of immune hyperreactivity, i.e., an IgE mediated (extrinsic) and a non-IgE mediated (intrinsic) form, are involved. The role of sensitization in children with AD is unclear, but both atopic predisposition and early sensitization is known to influence onset (4, 5), duration (6, 7) and severity (5, 8). Food allergy is reported to be associated with AD (9–12), however only few studies have addressed the causal relationship (13–16). The aim of this study was to describe the relapsing pattern of AD in children during the first 6 yr of life in a popula- tion-based cohort with focus on sensitization and prognosis. Materials and methods Study design The Danish Allergy Research Centre (DARC) cohort is a population-based/unselected, non- interventional, single-center birth cohort, includ- ing 562 probands, born at Odense University Hospital, Denmark. They were recruited from a random sample of all children (n = 1095) born within the first 14 days of each months from November 1998 to November 1999. Around 435 Eller E, Kjaer HF, Høst A, Andersen KE, Bindslev-Jensen C. Development of Atopic Dermatitis in the DARC birth cohort. Pediatr Allergy Immunol 2009: 21: 307–314. Ó 2009 John Wiley & Sons A/S The aim was to describe the relapsing pattern, sensitization and prog- nosis 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 ‡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. Esben Eller 1 , Henrik Fomsgaard Kjaer 1 , Arne Høst 2 , Klaus Ejner Andersen 1 and Carsten Bindslev-Jensen 1 1 Department of Dermatology, 2 Department of Pediatrics, Odense University Hospital, Odense C, Denmark Key words: atopic dermatitis; birth cohort; food allergy; prediction; sensitization; food hypersensitivity; prevalence; atopic eczema; prognosis Esben Eller, Allergy Centre, Department of Dermatology, Odense University Hospital, Sdr. Boulevard 29, DK-5000 Odense C Tel.: +45 6541 2717; (Alt. +45 2711 6181) Fax: +45 6312 1507 E-mail: esben.eller@ouh.regionsyddanmark.dk Accepted 10 March 2009 Pediatr Allergy Immunol 2010: 21: 307–314 DOI: 10.1111/j.1399-3038.2009.00914.x Ó 2009 John Wiley & Sons A/S PEDIATRIC ALLERGY AND IMMUNOLOGY 307