Decreased importance of environmental risk factors for childhood asthma from 1996 to 2006
2015 (English)In: Clinical and Experimental Allergy, ISSN 0954-7894, E-ISSN 1365-2222, Vol. 45, no 1, 146-153 p.Article in journal (Refereed) Published
BACKGROUND: The large increase in asthma prevalence continues in several, but not all areas. Despite the individual risk factors that have been identified, the reasons for the observed trends in prevalence are largely unknown.
OBJECTIVE: This study sought to characterize what trends in risk factors accompanied trends in asthma prevalence.
METHODS: Two population-based cohorts of 7-8-year-old children from the same Swedish study areas examined by expanded ISAAC questionnaires were compared 10 years apart. In 1996 3,430 (97% participation) and in 2006 2,585 (96% participation) questionnaires were completed. A subset was skin-prick tested: in 1996, 2,148 (88% participation) and in 2006, 1,700 (90% participation) children. The adjusted population attributable fraction (aPAF) was calculated using the prevalence and multivariate odds ratio of each risk factor.
RESULTS: The prevalence of current asthma and wheeze were similar in 1996 and 2006. Allergic sensitisation however increased from 21% to 30%. The prevalence of parental asthma increased from 17% to 24% while respiratory infections and maternal smoking decreased (60% to 29% and 32% to 16%, respectively). The aPAFs of non-environmental risk factors for current asthma increased 1996-2006: Allergic sensitization from 35% to 41%, parental asthma from 27% to 45% and male sex from 20% to 25%. Conversely, the aPAFs of environmental risk factors decreased: Respiratory infections from 36% to 32% and damp home and maternal smoking from 14% and 19% respectively to near zero in 2006.
CONCLUSIONS AND CLINICAL RELEVANCE: From 1996 to 2006 the non-environmental risk factors parental asthma, allergic sensitisation and male sex had an increasing or constant importance for current asthma in 7-8-year-old children. The importance of the environmental exposures damp home, respiratory infections and maternal smoking decreased. This counter-balancing in risk factors may explain the level prevalence of current asthma.
Place, publisher, year, edition, pages
2015. Vol. 45, no 1, 146-153 p.
asthma, children, epidemiology, population-attributable fraction, risk factors, wheeze
Environmental Health and Occupational Health
IdentifiersURN: urn:nbn:se:umu:diva-95999DOI: 10.1111/cea.12439ISI: 000346910800017PubMedID: 25323476OAI: oai:DiVA.org:umu-95999DiVA: diva2:762215