Worldwide time trends in the prevalence of symptoms of asthma, allergic rhinoconjunctivitis, and eczema in childhood: ISAAC Phases One and Three repeat multicountry cross-sectional surveys

TitleWorldwide time trends in the prevalence of symptoms of asthma, allergic rhinoconjunctivitis, and eczema in childhood: ISAAC Phases One and Three repeat multicountry cross-sectional surveys
Publication TypeJournal Article
AuthorsM Asher, Innes, Stephen Montefort, Bengt Björkstén, Christopher K. W. Lai, David P. Strachan, Stephan K. Weiland, and Hywel Williams
JournalThe Lancet
Volume368
Issue9537
Pagination733-743
ISSN0140-6736
Abstract

SummaryBackground
Data for trends in prevalence of asthma, allergic rhinoconjunctivitis, and eczema over time are scarce. We repeated the International Study of Asthma and Allergies in Childhood (ISAAC) at least 5 years after Phase One, to examine changes in the prevalence of symptoms of these disorders.
Methods
For the ISAAC Phase Three study, between 2002 and 2003, we did a cross-sectional questionnaire survey of 193 404 children aged 6–7 years from 66 centres in 37 countries, and 304 679 children aged 13–14 years from 106 centres in 56 countries, chosen from a random sample of schools in a defined geographical area.
Findings
Phase Three was completed a mean of 7 years after Phase One. Most centres showed a change in prevalence of 1 or more SE for at least one disorder, with increases being twice as common as decreases, and increases being more common in the 6–7 year age-group than in the 13–14 year age-group, and at most levels of mean prevalence. An exception was asthma symptoms in the older age-group, in which decreases were more common at high prevalence. For both age-groups, more centres showed increases in all three disorders more often than showing decreases, but most centres had mixed changes.
Interpretation
The rise in prevalence of symptoms in many centres is concerning, but the absence of increases in prevalence of asthma symptoms for centres with existing high prevalence in the older age-group is reassuring. The divergent trends in prevalence of symptoms of allergic diseases form the basis for further research into the causes of such disorders.

Notes

'Another paper on the ISAAC results.  It talks about the overall results, rather than being Singapore-specific.  Some of the testing centers saw increases in asthma rates and other allergy rates, while others saw decreases, and others saw no changes or mixed changes.\n - erikbigras'

URLhttp://www.sciencedirect.com/science/article/pii/S0140673606692830
DOI10.1016/S0140-6736(06)69283-0
Short TitleWorldwide time trends in the prevalence of symptoms of asthma, allergic rhinoconjunctivitis, and eczema in childhood