European study of asthma. Prevalence of atopy in young adults of 5 areas in Spain. Spanish Group of European Asthma Study

BACKGROUND: The aim of the current study is to show the prevalence of atopy in five Spanish areas, and its variability according to area, age and gender. PATIENTS AND METHODS: From a populational based sample of 16,884 individuals aged 20 to 44 years-old, we obtained a randomized 20% subsample (n = 3,310). Participants performed specific IgE measurements, skin prick tests, forced spirometries and metacholine challenges to measure bronchial hyperresponsiveness. The response rate was 40%, and 1,313 individuals were finally included in the study. Specific atopy to the following aeroallargens was determined: cat dander, Cladosporium, Dermatophagoides, Phleum, Parietaria, birch, Alternaria, ambrosia, olive, rye grass and dog dander. RESULTS: The global prevalence of atopy (detectable specific antibodies IgE in serum and/or skin reactivity) widely varied by area, skin reactivity ranking in males from a minimum in Albacete (24.6%; 95% CI: 18-33) to a maximum in Huelva (39.6%; 95% CI: 30-53), and in females ranking from a minimun in Galdakao (10.3%; 95% CI: 6-17) to a maximum in Barcelona (28.8%; 95% CI: 19-43). Considering separately seropositivity and skin reactivity we observed a similar trend. Males showed a higher prevalence of global atopy (40.1%) than females (29.4%). Our data indicate that there is a decrease in the prevalence of atopy according to age in the general population, but only significant in men. Dermatophagoides pteronyssinus is the most common allergen in all ares but Albacete, where the most common allergen is the olive pollen. CONCLUSIONS: By means of a standard methodology, we report population data of the prevalence of atopy in five Spanish areas. The distribution of the prevalence of atopy varies widely in the five areas surveyed, according to the composition of the most common environmental allergens.