Relationship between rhinitis symptoms and allergic sensitization in phase 2 of the International Study of Asthma and Allergies in Childhood (ISAAC)

Relationship between rhinitis symptoms and allergic sensitization in phase 2 of the International Study of Asthma and Allergies in Childhood (ISAAC) Background: The prevalence of rhinitis varies widely across the world. Literature has mainly focused on allergic rhinitis, however some studies indicate the importance of non-allergic noninfectious rhinitis. We investigated the relation between atopy and rhinitis symptoms worldwide. Methods: Cross-sectional studies of random samples of 8- to 12-year old children (n = 1,000 per centre) were performed according to the standardized methodology of ISAAC Phase 2. Thirty study centres in 22 countries worldwide participated and reflect a wide range of rhinitis prevalence and living conditions. Symptom data were collected by parental questionnaires (n = 54,178) and a skin prick test (n = 31,759) for common aeroallergens was performed. Results: The population attributable fraction (PAF) for rhinoconjunctivitis with regard to allergic sensitization varied from 0 to 71% for seasonal allergens and from 0 to 41% for perennial allergens, respectively. It was higher in affluent countries (36 and 25%, for seasonal and perennial allergens, respectively) than in nonaffluent countries (1.3 and 12.6%, respectively). For rhinitis without conjunctivitis, the PAF for perennial allergens was 8 and 4% for affluent and nonaffluent countries, respectively, whereas no significant PAF was found for seasonal allergens. Conclusion: Allergic sensitization can explain only a limited proportion of rhinitis symptoms, especially in nonaffluent countries. Rhinitis without conjunctivitis seems to reflect mainly nonatopic rhinitis. This suggests that the importance of other, environmental risk factors for noninfectious rhinitis have been generally underemphasized.