Background Preschool wheeze is an important problem worldwide. No comparative population-based studies covering different countries have previously been undertaken.
Objective To assess the prevalence of early childhood wheeze across Europe and evaluate risk factors focusing on food allergy, breast feeding and smoke exposure.
Methods Infants from nine countries were recruited into the EuroPrevall birth cohort. At 12 and 24 months, data on wheeze, allergic signs/symptoms, feeding, smoke exposure, infections and day care attendance were collected using questionnaires. Poisson regression was used to assess risk factors for wheeze.
Results 12 049 infants were recruited. Data from the second year of life were available in 8805 (73.1%). The prevalence of wheeze in the second year of life ranged from <2% in Lodz (Poland) and Vilnius (Lithuania) to 13.1% (95% CI 10.7% to 15.5%) in Southampton (UK) and 17.2% (95% CI 15.0% 19.5%) in Reykjavik (Iceland). In multivariable analysis, frequent lower respiratory tract infections in the first and second years of life (incidence rate ratio (IRR) 1.9 (95% CI 1.3 to 2.6) and 2.5 (95% CI 1.9 to3.4), respectively), postnatal maternal smoking (IRR 1.6, 95% CI 1.1 to 2.4), day care attendance (IRR 1.6, 95% CI 1.1 to 2.5) and male gender (IRR 1.3, 95% CI 1.0 to 1.7) were associated with wheeze. The strength of their association with wheeze differed between countries. Food allergy and breast feeding were not independently associated with wheeze.
Conclusion The prevalence of early childhood wheeze varied considerably across Europe. Lower respiratory tract infections, day care attendance, postnatal smoke exposure and male gender are important risk factors. Further research is needed to identify additional modifiable risk factors that may differ between countries.
- asthma epidemiology
- paediatric asthma
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Contributors ENCM was coordinator of the EuroPrevall project; KB was principal investigator of the birth cohort study. ACS, GR, KEG and AM performed the statistical analyses; TK, LG and VC provided statistical and epidemiological advice. ACS and GR drafted the manuscript. All authors reviewed and approved the final manuscript.
Funding The EuroPrevall birth cohort study was conducted within the collaborative research initiative EuroPrevall, an integrated project funded by the European Commission under the 6th Framework Programme (FOOD-CT-2005-514000), and Integrated Approaches to Food Allergy and Allergy Risk Management, a 7th Framework Collaborative Project (FP7-KBBE-2012-6). The UK birth cohort and the analysis for this paper was funded by the UK Food Standards Agency (T07046 and FS305019).
Competing interests GR received grants from the EU FP6 Programme and UK Food Standards Agency during the conduct of the study; KEG has received educational grants from Nutrica and speaker fees from Nutrica and Abbott; TK has received grants from the EU FP7 Programme outside of the submitted work; STS received grants from Landspitali University Hospital Science Fund, GlaxoSmithKline and the Icelandic Student Innovation Fund during the conduct of the study and has received non-financial support from Novartis and Thermo Fisher outside of the submitted work; ENCM has received grants from the UK Biological and Biotechnological Sciences Research Council, DBV Technologies, Reacta Biotech Ltd, the Medical Research Council, Innovate and the North West Lung Centre Charity outside of the submitted work and is founding director of Reacta Biotech Ltd; KB has received funding for research activities from the European Union, German Research Foundation, Berliner Sparkasse, BEA-Stiftung, Food Allergy and Anaphylaxis Network, Food Allergy Initiative, Danone, Thermo Fisher and DST Diagnostics. Other authors have no competing interests to declare.
Ethics approval Ethics approval was obtained from the relevant ethics committee in each country involved in the study.
Provenance and peer review Not commissioned; externally peer reviewed.
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