title: Age at onset of asthma and allergen sensitization early in life.
abstract: BACKGROUND
  Epidemiological evidence indicates that the age at onset of asthma and allergen sensitization in early life is decreasing in people from Western countries. To explore latent trends, we conducted a retrospective examination of the age at onset of asthma and specific IgE antibodies against inhalant allergens in Japanese asthmatic children.
  
  
  METHODS
  We conducted a case series study of 103 consecutive children with atopic type of asthma (aged 2 years to 16 years, mean age 9.4 ± 3.4 years). Diagnoses of asthma and allergic rhinitis were defined according to Japanese guidelines. The onset of asthma and allergic rhinitis was also defined as any report of asthma and allergic rhinitis confirmed by a physician. Allergen sensitization was evaluated as specific serum IgE levels for 9 common inhalant allergens in peripheral blood. Atopic type of asthma was defined as a being positive for at least one aeroallergen.
  
  
  RESULTS
  Mean age at asthma onset was 2.3 ± 1.9 years, which is slightly lower than that of previous reports, including those published in Japan. A high prevalence rate of up to 80% was found for perennial antigens including Dermatophagoides spp. and house dust, as reported previously. Notably, some of the children aged at 1 year tested positive for these allergens.
  
  
  CONCLUSIONS
  The age at onset of asthma seems to be decreasing in comparison with previous reports. Furthermore, the age at onset of allergen sensitization against inhalant allergens appears to follow this trend.
authors.affiliation: Department of Allergy and Immunology, Gunma Children's Medical Center, Gunma, Japan.
authors.forename: Masahiko
authors.initials: M
authors.lastname: Kato
authors.affiliation: Department of Allergy and Immunology, Gunma Children's Medical Center, Gunma, Japan.
authors.forename: Yoshiyuki
authors.initials: Y
authors.lastname: Yamada
authors.affiliation: Department of Nephrology, Gunma Children's Medical Center, Gunma, Japan.
authors.forename: Kenichi
authors.initials: K
authors.lastname: Maruyama
authors.affiliation: Department of Hematology and Oncology, Gunma Children's Medical Center, Gunma, Japan.
authors.forename: Yasuhide
authors.initials: Y
authors.lastname: Hayashi
mesh_terms: D000293:Adolescent; D000367:Age Factors; D017668:Age of Onset; D000485:Allergens / Q000276:immunology*; D000818:Animals; D000918:Antibody Specificity / Q000276:immunology; D001249:Asthma / Q000453:epidemiology* / Q000276:immunology*; D002648:Child; D002675:Child, Preschool; D005260:Female; D006801:Humans; D007073:Immunoglobulin E / Q000097:blood / Q000276:immunology; D008297:Male; D012189:Retrospective Studies; D012307:Risk Factors
chemical_list: D000485:Allergens; D007073:Immunoglobulin E