Increase in sensitization to common airborne allergens among adults — two population-based studies 15 years apart
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.
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.
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).
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.
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“In conclusion, from 1994 to 2009 the prevalence of allergic sensitization to the major
allergens in the studied area, as well as multi-sensitization, increased significantly among
adults. The overall prevalence of sensitization to at least one allergen increased also, howevernot significantly. Young age and a family history of allergy were the most important risk factors. Additionally, urban living was associated with an increased risk for allergic sensitization, especially to pollen. Our study results of an on-going increase of allergic sensitization emphasizes the need for further studies of environmental risk factors as well as clinical effects of the increased prevalence.”