Worldwide variations in the prevalence of symptoms of atopic eczema in the international study of asthma and allergies in childhood,☆☆,,★★

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Abstract

Background: Little is known about the prevalence of atopic eczema outside Northern Europe. Objectives: We sought to describe the magnitude and variation in the prevalence of atopic eczema symptoms throughout the world. Methods: A cross-sectional questionnaire survey was conducted on random samples of schoolchildren aged 6 to 7 years and 13 to 14 years from centers in 56 countries throughout the world. Those children with a positive response to being questioned about the presence of an itchy relapsing skin rash in the last 12 months that had affected their skin creases were considered to have atopic eczema. Children whose atopic eczema symptoms resulted in sleep disturbance for 1 or more nights per week were considered to have severe atopic eczema. Results: Complete data was available for 256,410 children aged 6 to 7 years in 90 centers and 458,623 children aged 13 to 14 years in 153 centers. The prevalence range for symptoms of atopic eczema was from less than 2% in Iran to over 16% in Japan and Sweden in the 6 to 7 year age range and less than 1% in Albania to over 17% in Nigeria for the 13 to 14 year age range. Higher prevalences of atopic eczema symptoms were reported in Australasia and Northern Europe, and lower prevalences were reported in Eastern and Central Europe and Asia. Similar patterns were seen for symptoms of severe atopic eczema. Conclusions: Atopic eczema is a common health problem for children and adolescents throughout the world. Symptoms of atopic eczema exhibit wide variations in prevalence both within and between countries inhabited by similar ethnic groups, suggesting that environmental factors may be critical in determining disease expression. Studies that include objective skin examinations are required to confirm these findings. (J Allergy Clin Immunol 1999;103:125-38.)

Section snippets

METHODS

The ISAAC Phase One study used core questionnaires designed to assess the prevalence and severity of atopic eczema, asthma, and allergic rhinoconjunctivitis symptoms in defined populations. The methods have been described in detail in the ISAAC manual15 and in an article concerning rationale and methods.11 Ethical approval was obtained locally for the centers.

RESULTS

Response rates for individual centers were generally very high (73% of all centers with response rates between 90% and 100%, 22% between 80% and 89%, 5% between 70% and 79%, and 1 center with a response rate of 66% for those aged 13 to 14 years). Exact response rates and the various languages used in the translated questionnaires are presented elsewhere.13 Table II shows the prevalence of symptoms of atopic eczema in children aged 6 to 7 years from 90 centers and children aged 13 to 14 years in

DISCUSSION

For the first time, prevalence data for symptoms of atopic eczema based on data from a standardized questionnaire encompassing responses from persons with a wide range of physical, socioeconomic, and ethnic backgrounds in all major world regions has been made available. Most of the previous surveys of atopic eczema prevalence have been conducted in Northern Europe,7, 10 and this may have given the impression that atopic eczema is mainly a disease of developed countries in cooler climates. This

Acknowledgements

The Writing Committee consisted of H. C. Williams, C. F. Robertson, and A. W. Stewart. The ISAAC Steering Committee consisted of N. Aït-Khaled, G. Anabwani, H. R. Anderson, M. I. Asher (Chair), R. Beasley (Coordinator Phase One), B. Björkstén, M. Burr, T. Clayton, J. Crane, P. Ellwood, U. Keil, C. K. W. Lai, J. Mallol, F. Martinez, E. A. Mitchell, S. Montefort, N. Pearce, C. F. Robertson, J. R. Shah, B. Sibbald, A. W. Stewart, D. Strachan, E. von Mutius, S. K. Weiland (Coordinator Phase Two),

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    Supported by the Health Research Council of New Zealand, the Asthma and Respiratory Foundation of New Zealand, the National Child Health Research Foundation, the Hawke’s Bay Medical Research Foundation, the Waikato Medical Research Foundation, Glaxo Wellcome New Zealand, and Astra New Zealand.

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    The ISAAC website address is http://isaac.auckland.ac.nz/.

    Reprint requests: Hywel Williams, PhD, Queen’s Medical Centre, University Hospital, Nottingham, NG7 2UH, United Kingdom.

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