title: Increase in sensitization to common airborne allergens among adults - two population-based studies 15 years apart.
abstract: BACKGROUND
  Studies on time trends of allergic sensitization among adults are rare. The aim of the study was to compare the prevalence of allergic sensitization to common airborne allergens among adults 15 years apart and to identify risk factors for allergic sensitization.
  
  
  METHODS
  Clinical examinations including skin prick test (SPT) and structured interviews were performed in two random population samples in 1994 and 2009. Furthermore, specific IgE was analyzed in 2009. SPT data were available for 483 subjects in 1994 and for 463 subjects in 2009 in ages 20-60 years. Specific IgE was analyzed in 692 subjects in ages 20-79 years.
  
  
  RESULTS
  Sensitization to cat (16% to 26%, p < 0.001), dog (13% to 25%, p < 0.001), birch (13% to 18%, p = 0.031) and timothy (12% to 21%, p < 0.001), based on SPT, increased significantly from 1994 to 2009. Sensitization to any positive SPT increased from 35% to 39%, p = 0.13.The proportion of having ≥3 positive SPT reactions increased from 40% to 56%, p = 0.002. The sensitization pattern yielded similar results based on specific IgE. Risk factors for allergic sensitization were having a family history of allergy (OR 3.1, 95% CI 2.0-4.8 for any positive SPT; OR 2.7, 95% CI 1.8-4.0 for any elevated IgE) and urban living (OR 1.7, 95% CI 1.0-2.7; OR 1.5, 95% CI 1.0-2.4).
  
  
  CONCLUSIONS
  The prevalence of allergic sensitization to major airborne allergens as well as multi-sensitization increased significantly between the study years. Young age, a family history of allergy and urban living were significant risk factors for allergic sensitization.
authors.affiliation: The OLIN studies, Norrbotten County Council, Robertsviksgatan 9, Luleå, S-971 89, Sweden ; Department of Respiratory Medicine and Allergology, Sunderby Central Hospital of Norrbotten, Luleå, Sweden ; Department of Public Health and Clinical Medicine, Umeå University, Umeå, Sweden.
authors.forename: Katja
authors.initials: K
authors.lastname: Warm
authors.affiliation: The OLIN studies, Norrbotten County Council, Robertsviksgatan 9, Luleå, S-971 89, Sweden ; Department of Public Health and Clinical Medicine, Umeå University, Umeå, Sweden.
authors.forename: Anne
authors.initials: A
authors.lastname: Lindberg
authors.affiliation: The OLIN studies, Norrbotten County Council, Robertsviksgatan 9, Luleå, S-971 89, Sweden ; Institute of Medicine/Krefting Research Center, University of Gothenburg, Gothenburg, Sweden.
authors.forename: Bo
authors.initials: B
authors.lastname: Lundbäck
authors.affiliation: The OLIN studies, Norrbotten County Council, Robertsviksgatan 9, Luleå, S-971 89, Sweden ; Department of Public Health and Clinical Medicine, Umeå University, Umeå, Sweden.
authors.forename: Eva
authors.initials: E
authors.lastname: Rönmark
keywords: Allergic sensitization; Epidemiology; IgE; Population study; Prevalence; Skin prick test