Age at Onset of Asthma and Allergen Sensitization Early in Life

Background: Epidemiological evidence indicates that the age at onset of asthma and allergen sensitization in early life is decreasing in people from Western countries. To explore latent trends, we conducted a retrospective examination of the age at onset of asthma and specific IgE antibodies against inhalant allergens in Japanese asthmatic children. Methods: We conducted a case series study of 103 consecutive children with atopic type of asthma (aged 2 years to 16 years, mean age 9.4 +/- 3.4 years). Diagnoses of asthma and allergic rhinitis were defined according to Japanese guidelines. The onset of asthma and allergic rhinitis was also defined as any report of asthma and allergic rhinitis confirmed by a physician. Allergen sensitization was evaluated as specific serum IgE levels for 9 common inhalant allergens in peripheral blood. Atopic type of asthma was defined as a being positive for at least one aeroallergen. Results: Mean age at asthma onset was 2.3 +/- 1.9 years, which is slightly lower than that of previous reports, including those published in Japan. A high prevalence rate of up to 80% was found for perennial antigens including Dermatophagoides spp. and house dust, as reported previously. Notably, some of the children aged at 1 year tested positive for these allergens. Conclusions: The age at onset of asthma seems to be decreasing in comparison with previous reports. Furthermore, the age at onset of allergen sensitization against inhalant allergens appears to follow this trend.