Artikel
International variations in the prevalence of rhinoconjunctivitis and the role of atopy: results from phase two of the International Study of Asthma and Allergies in Childhood (ISAAC)
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Veröffentlicht: | 6. September 2007 |
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Background: The relative importance of atopy in the etiology of non-infectious rhinitis is still unclear. We investigated the association of rhinoconjunctivitis with atopic sensitization to seasonal and perennial allergens.
Methods: Random samples (n 1000) of children (8-12 years) in 30 centres in 22 countries were studied with standardized questionnaires on occurrence and severity of allergic diseases. Skin prick tests were performed for six common aeroallergens of seasonal and perennial occurrence. In 18 centres additional allergens of local relevance were included
Results: 12 months prevalence of rhinoconjunctivitis symptoms ranged from 1.5% to 24.5%. The prevalence of sensitization ranged from 0.1% to 25.8% for seasonal allergens and from 1.4% to 45.2% for perennial allergens.
The prevalence rate ratio (PRR) for the association between rhinoconjunctivitis and seasonal allergens (adjusted for perennial allergens) ranged from 0.5 to 9.0%. The combined PRR was higher in affluent countries (gross national income 9200$ per capita per year) than in non-affluent countries (PRR = 3.6; 95%-CI:2.6-5.0 and PRR = 1.6; 95%-CI:1.1-2.4, respectively). For perennial allergens the PRR (adjusted for seasonal allergens) ranged from 0.8 to 4.1. The combined PRR was 2.2 (95%-CI:1.8-2.6) for affluent countries and 1.5 (95%-CI:1.1-2.1) for non-affluent countries. The combined adjusted population attributable fraction for seasonal allergens was 35.9% (95%-CI:23.6%-46.2%) and 1.3% (95%-CI:0%-2.8%) for affluent and non-affluent countries, respectively. For perennial allergens, the combined adjusted population attributable fraction was 25.0% (95%-CI:18.1%-31.4%) for affluent countries and 12.6% (95%-CI:2.7%-21.6%) for non-affluent countries.
Conclusions: The association of rhinoconjunctivitis with sensitization to seasonal allergens varies strongly worldwide and is weaker among non-affluent centres, where it is not significant in some centres. This difference is also visible for perennial allergens, though less pronounced. Moreover, perennial allergens seem to have more relative importance in non-affluent centres. Overall, the influence of sensitization seems to be weaker than has been often assumed.