title: Increase in Allergic Sensitization in Schoolchildren: Two Cohorts Compared 10 Years Apart.
abstract: BACKGROUND
  Time trends of incidence of allergic sensitization are unknown and recent trends of prevalence and risk factors are lacking.
  
  
  OBJECTIVE
  To estimate the incidence, prevalence, remission, risk factors, and time trends for allergic sensitization among schoolchildren followed from age 7 to 8 years to age 11 to 12 years.
  
  
  METHODS
  In 2006, all children in grades 1 and 2 aged 7 to 8 years in 2 municipalities in northern Sweden were invited to a questionnaire survey and to skin prick testing to 10 common airborne allergens. The cohort was reexamined in 2010, with additional blood sampling for specific IgE. Participation rates were 90% (n = 1700) at age 7 to 8 years and 85% (n = 1657) at age 11 to 12 years. The results were compared with a cohort examined by identical methods 10 years earlier.
  
  
  RESULTS
  The prevalence of positive skin prick test result to any allergen increased from 30% at age 7 to 8 years to 41% at age 11 to 12 years (P < .001). The cumulative 4-year incidence was 18%, while remission was low. Sensitization to pollen and furred animals was most common. A family history of allergy was significantly associated with incident sensitization, whereas the presence of furred animals at home was negatively associated. The prevalence at age 7 to 8 years and at age 11 to 12 years and the 4-year incidence were all significantly higher compared with the cohort examined 10 years earlier.
  
  
  CONCLUSIONS
  The prevalence of allergic sensitization increased by age as a consequence of a high incidence and a low remission. The trends of increasing incidence and prevalence among schoolchildren imply future increases in the prevalence of allergic diseases.
authors.affiliation: Department of Public Health and Clinical Medicine, Division of Occupational and Environmental Medicine, the OLIN Unit, Umeå University, Umeå, Sweden.
authors.forename: Joakim
authors.initials: J
authors.lastname: Bunne
authors.affiliation: Department of Public Health and Clinical Medicine, Division of Occupational and Environmental Medicine, the OLIN Unit, Umeå University, Umeå, Sweden.
authors.forename: Helena
authors.initials: H
authors.lastname: Moberg
authors.affiliation: Department of Public Health and Clinical Medicine, Division of Occupational and Environmental Medicine, the OLIN Unit, Umeå University, Umeå, Sweden; Department of Health Sciences, Division of Nursing, Luleå University of Technology, Luleå, Sweden.
authors.forename: Linnea
authors.initials: L
authors.lastname: Hedman
authors.affiliation: Department of Public Health and Clinical Medicine, Division of Occupational and Environmental Medicine, the OLIN Unit, Umeå University, Umeå, Sweden.
authors.forename: Martin
authors.initials: M
authors.lastname: Andersson
authors.affiliation: Department of Women's and Children's Health, Karolinska Institutet, Stockholm, Sweden.
authors.forename: Anders
authors.initials: A
authors.lastname: Bjerg
authors.affiliation: Krefting Research Centre, Institute of Medicine, University of Gothenburg, Gothenburg, Sweden.
authors.forename: Bo
authors.initials: B
authors.lastname: Lundbäck
authors.affiliation: Department of Public Health and Clinical Medicine, Division of Occupational and Environmental Medicine, the OLIN Unit, Umeå University, Umeå, Sweden. Electronic address: eva.ronmark@nll.se.
authors.forename: Eva
authors.initials: E
authors.lastname: Rönmark
mesh_terms: D000485:Allergens / Q000276:immunology; D002648:Child; D015331:Cohort Studies; D005260:Female; D006197:Hair / Q000276:immunology; D006801:Humans; D006967:Hypersensitivity / Q000453:epidemiology* / Q000276:immunology*; D007114:Immunization; D015994:Incidence; D008297:Male; D011058:Pollen / Q000276:immunology; D011153:Population; D015995:Prevalence; D012307:Risk Factors; D012882:Skin Tests; D011795:Surveys and Questionnaires; D013548:Sweden / Q000453:epidemiology; D013997:Time Factors
chemical_list: D000485:Allergens
keywords: Allergic sensitization; Incidence; Longitudinal study; Prevalence; Risk factors; Schoolchildren