The influence of age and gender on sensitization to aero-allergens.

Boys run a higher risk for atopy than girls but this gender difference is less pronounced in adulthood. The underlying mechanisms and the exact timing of this decrease in male/female ratio remain unclear. The aim of this study was to evaluate the effect of age and gender on sensitization in schoolchildren. A cross-sectional study was performed in an unbiased community population of 2021 Belgian schoolchildren, aged 3.4-14.8 yr. The overall sensitization and the sensitization for mites, mixed grass pollens and tree pollens increased significantly with increasing age. Male sex was strongly associated with sensitization (OR(adj) 2.0, 98% CI 1.6-2.4). Male predominance was more obvious in children under the age of 8 yr. After the age of 8 male predominance persisted, but a significant increase in sensitized females occurred. Our data demonstrate a significant increase in prevalence of sensitization with age and a significant decrease in male/female ratio of sensitization after the age of 8 yr, although a male predominance persists. These data are the first published data ever that document this change in male/female ratio in sensitization at this age.