title: Worldwide time trends for symptoms of rhinitis and conjunctivitis: Phase III of the International Study of Asthma and Allergies in Childhood.
abstract: In Phase III of the International Study of Asthma and Allergies in Childhood (ISAAC) time trends in the prevalence of rhinoconjunctivitis symptoms were analysed. Cross-sectional questionnaire surveys with identical protocols and questionnaires were completed a mean of 7 yr apart in two age groups comprising 498,083 children. In the 13- to 14-yr age group 106 centres in 56 countries participated, and in the 6- to 7-yr age group 66 centres in 37 countries participated. A slight worldwide increase in rhinoconjunctivitis prevalence was observed, but the variations were large among the centres and there was no consistent regional pattern. Prevalence increases in the older children exceeding 1% per year were recorded in 13 centres, including 3 of 9 centres in Africa, 2 of 15 in Asia-Pacific, 1 of 8 in India, 3 of 15 in Latin America, 3 of 9 in Eastern Europe and 1 of 34 in Western and Northern Europe. Decreasing rhinoconjunctivititis prevalence of similar magnitude was only seen in four centres. The changes were less pronounced in the 6- to 7-yr-old children and only in one centre did any change exceed 1% per year. The decrease in highest prevalence rates in ISAAC Phase I suggests that the prevalence has peaked in those regions. An increase was recorded in several centres, mostly in low and mid-income countries. The increases were more pronounced in the older age group, suggesting that environmental influences on the development of allergy may not be limited to early childhood.
authors.affiliation: Institute of Environmental Medicine, Karolinska Institutet, Stockholm, Sweden. bengt.bjorksten@ki.se
authors.forename: Bengt
authors.initials: B
authors.lastname: Björkstén
authors.forename: Tadd
authors.initials: T
authors.lastname: Clayton
authors.forename: Philippa
authors.initials: P
authors.lastname: Ellwood
authors.forename: Alistair
authors.initials: A
authors.lastname: Stewart
authors.forename: David
authors.initials: D
authors.lastname: Strachan
mesh_terms: D000293:Adolescent; D000367:Age Factors; D001249:Asthma / Q000453:epidemiology*; D002648:Child; D003231:Conjunctivitis / Q000453:epidemiology*; D003430:Cross-Sectional Studies; D014943:Global Health; D006801:Humans; D006967:Hypersensitivity / Q000453:epidemiology*; D009017:Morbidity / Q000639:trends; D015995:Prevalence; D012221:Rhinitis, Allergic, Perennial / Q000453:epidemiology*; D006255:Rhinitis, Allergic, Seasonal / Q000453:epidemiology*; D011795:Surveys and Questionnaires; D013997:Time Factors