Pets in the home and the development of pet allergy in adulthood. The Copenhagen Allergy Study

Background: The aim of the study was to investigate the association between exposure to cat and dog in the home and the development (incidence) of IgE sensitization to cat and dog. Methods: Participants in a population-based study of 15-69-year-olds in 1990 were invited to a follow-up in 1998. Serum IgE antibodies against common inhalant allergens was assessed in 734 subjects (participation rate 69.0%) on two occasions 8 years apart. Information about current or previous keeping of cats and dogs in the home was obtained in a questionnaire at baseline. Results: A cat in the home currently was significantly associated with the development of IgE sentisization to cat (adjusted odds ratio 8.4, 95% confidence interval (CI) 1.7-42.7). Moreover, an atopic predisposition in terms of IgE sensitization to allergens other than cat at baseline was an independent risk factor for the development of IgE sensitization to cat. A dog in the home was not significantly associated with the development of IgE sensitization to dog. Conclusions: In this adult population, exposure to a cat in the home increased the risk of developing IgE sensitization to cat. More prospective data are needed on this issue.