Mechanisms of AllergyFour-year incidence of allergic sensitization among schoolchildren in a community where allergy to cat and dog dominates sensitization: Report from the obstructive lung disease in northern sweden study group☆
Section snippets
Methods
We used questionnaires and skin prick tests (SPTs). SPTs were performed at the beginning of the study and 4 years later. A questionnaire was completed yearly. Consent for SPTs was obtained from parents. The ethical committee at the University Hospital of Northern Sweden in Umeå approved the study.
Prevalence and incidence
The prevalence of a positive SPT response to any of the tested allergens was 20.6% at age 7 and 8 years and had increased to 30.4% by age 11 and 12 years. At both ages, the most common allergen was cat, followed by dog, birch, and timothy grass (Fig 2). The prevalence of any positive SPT response at age 11 and 12 years among the 1870 children who were tested twice was 30.8%.
The cumulative incidence of any positive SPT response during the 4-year period was 13.8% among the 1478 children with a
Discussion
The incidence of sensitization to inhalant allergens over 4 years was high (13.8%) and resulted in an increase in prevalence from 20.6% at age 7 and 8 years to 30.4% 4 years later. The high incidence combined with the prospective nature of the study design and the size of the cohort allowed for an in-depth analysis of the risk factors for the onset of sensitization. The high participation rate, standardized methods, and close correlation between SPT results and in vitro IgE assays at age 7 and
Acknowledgements
We thank Kerstin Kemi-Björnström, Lena Gustafsson, and Aina Johnsson for collection of the data. ALK and Pharmacia-Upjohn are acknowledged for help with providing test material and GlaxoSmithKline and AstraZeneca for additional support.
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Supported by the Swedish Heart-Lung Foundation, the Swedish Foundation for Health Care Science and Allergy Research (Vårdal), the US National Institute of Allergy and Infectious Diseases (AI-20565 and AI-34607), the Swedish Asthma-Allergy Foundation, and Norrbotten's local health authorities.