title: Atopic endotype in childhood.
abstract: BACKGROUND
  The term atopic disorder is an early attempt to define specific endotypes of children with asthma, eczema, or both and increased IgE levels.
  
  
  OBJECTIVE
  We performed a longitudinal analysis of the relevance of the atopic endotype from birth to age 13 years.
  
  
  METHODS
  Allergic sensitization against 28 inhalant and food allergens was assessed at ½, 1½, 4, 6, and 13 years of age in 399 children from the Copenhagen Prospective Study on Asthma in Childhood2000 birth cohort by using both skin prick test responses and specific IgE levels. Asthma and eczema were diagnosed longitudinally by strictly adhering to predefined algorithms. Associations between allergic sensitization, asthma, and eczema were estimated by means of logistic regression, and a machine learning approach was used to identify temporal phenotype clusters of these traits.
  
  
  RESULTS
  Allergic sensitization showed no association with asthma through early childhood (0-6 years) when analyzed as any sensitization (odds ratio [OR] range, 0.78-1.29; P ≥ .48). However, at 13 years of age, any sensitization was associated with asthma (OR range, 4.02-5.94; all P < .001). In contrast, any sensitization was associated with eczema at ½, 1½, and 6 years of age (OR range, 2.06-6.02; P ≤ .01) and borderline associated at 4 years of age (OR, 1.61 [95% CI, 0.96-2.69]; P = .07) but not at 13 years of age (OR, 1.57 [95% CI, 0.78-3.16]; P = .21). We identified 4 latent patterns of disease development that were either dominated by sensitization (37%), eczema (26%), asthma (14%), or healthy status (24%).
  
  
  CONCLUSIONS
  We found very little interdependency between asthma, eczema, and allergic sensitization through childhood. The associations between those entities were strongly dependent on age, type of allergens, and method of testing for sensitization. Therefore, atopy in children is unlikely to represent a true endotype.
authors.affiliation: Copenhagen Prospective Studies on Asthma in Childhood, Herlev and Gentofte Hospital, University of Copenhagen, Copenhagen, Denmark.
authors.forename: Ann-Marie Malby
authors.initials: AM
authors.lastname: Schoos
authors.affiliation: Copenhagen Prospective Studies on Asthma in Childhood, Herlev and Gentofte Hospital, University of Copenhagen, Copenhagen, Denmark.
authors.forename: Bo Lund
authors.initials: BL
authors.lastname: Chawes
authors.affiliation: Copenhagen Prospective Studies on Asthma in Childhood, Herlev and Gentofte Hospital, University of Copenhagen, Copenhagen, Denmark; Department of Food Science, Faculty of Science, University of Copenhagen, Copenhagen, Denmark.
authors.forename: Morten Arendt
authors.initials: MA
authors.lastname: Rasmussen
authors.affiliation: Copenhagen Prospective Studies on Asthma in Childhood, Herlev and Gentofte Hospital, University of Copenhagen, Copenhagen, Denmark.
authors.forename: Joakim
authors.initials: J
authors.lastname: Bloch
authors.affiliation: Copenhagen Prospective Studies on Asthma in Childhood, Herlev and Gentofte Hospital, University of Copenhagen, Copenhagen, Denmark.
authors.forename: Klaus
authors.initials: K
authors.lastname: Bønnelykke
authors.affiliation: Copenhagen Prospective Studies on Asthma in Childhood, Herlev and Gentofte Hospital, University of Copenhagen, Copenhagen, Denmark. Electronic address: bisgaard@copsac.com.
authors.forename: Hans
authors.initials: H
authors.lastname: Bisgaard
mesh_terms: D000293:Adolescent; D000367:Age Factors; D000485:Allergens / Q000276:immunology; D001249:Asthma / Q000175:diagnosis / Q000276:immunology; D002648:Child; D002675:Child, Preschool; D004485:Eczema / Q000175:diagnosis / Q000276:immunology; D005260:Female; D006801:Humans; D006969:Hypersensitivity, Immediate / Q000175:diagnosis / Q000453:epidemiology / Q000276:immunology*; D007114:Immunization; D007073:Immunoglobulin E / Q000276:immunology; D007223:Infant; D008297:Male; D015995:Prevalence; D011446:Prospective Studies; D012882:Skin Tests; D012959:Socioeconomic Factors
chemical_list: D000485:Allergens; D007073:Immunoglobulin E
keywords: Endotype; asthma; children; eczema; sensitization; skin prick test; specific IgE