Atopic dermatitis and skin disease
The role of atopic sensitization in flexural eczema: Findings from the International Study of Asthma and Allergies in Childhood Phase Two

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Background

The association between allergic sensitization and eczema has been debated for years.

Objective

We sought to determine and compare the strength of the association between allergen skin sensitization and eczema in both developing and industrialized countries.

Methods

Twenty-eight thousand five hundred ninety-one randomly selected 8- to 12-year-old schoolchildren in 20 countries were physically examined for flexural eczema and received skin prick testing to Dermatophagoides pteronyssinus, Dermatophagoides farinae, cat hair, Alternaria tenuis, mixed tree and grass pollen, and allergens of local relevance.

Results

The age- and sex-adjusted odds ratios (ORs) for a positive association between flexural eczema and atopy ranged between 0.74 (95% CI, 0.31-1.81) and 4.53 (95% CI, 1.72-11.93), with a significantly stronger association in affluent compared with nonaffluent countries (combined age- and sex-adjusted ORaffluent = 2.69 [95% CI, 2.31-3.13] and ORnonaffluent = 1.17 [95% CI, 0.81-1.70]). The combined population attributable fraction for atopy in flexural eczema was 27.9% for affluent and 1.2% for nonaffluent-country centers. Correlating gross national per-capita income with either ORs or population attributable fractions for atopy in flexural eczema confirmed a highly significant positive association (P = .006 and P < .001, respectively).

Conclusions

The association between atopy and flexural eczema is weak and more variable than previously suggested, and the strength of this association is positively linked to gross national income.

Section snippets

Methods

The rationale and methods of ISAAC Phase Two have been described elsewhere in detail.6 In brief and with reference to this article, ISAAC Phase Two was conducted among 8- to 12-year-old schoolchildren to evaluate the prevalence and risk factors of allergic disease between populations. Study centers were required to randomly select at least 10 schools from a complete sampling frame of schools in defined geographic areas, and children (n ≥ 1000 per center) attending classes with a majority of 9-

Results

The mean participation rate across study centers was 63% for skin prick testing and 62% for skin examination. Both measurements were available for 28,591 children.

Discussion

Our study tested the strength of the association between atopy and flexural eczema. Although we found statistically significant associations between flexural eczema and skin prick test response positivity in almost all affluent countries, the association was weaker and statistically nonsignificant for most study centers in nonaffluent nations. It is the inconsistency of this association across pediatric populations that suggests that allergic sensitization is unlikely to be a main cause of

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    The coordination and central laboratory analyses of the European centre were supported by the Fifth Framework Programme of the European Commission, Brussels, Belgium (QLK4-CT-1999-01288). Pharmacia Diagnostics (Uppsala, Sweden) made reagents available at a nominal cost.

    Disclosure of potential conflict of interest: M. Clausen has received grant support from the European Union. The rest of the authors have declared that they have no conflict of interest.

    The members of the International Study of Asthma and Allergies in Childhood Phase Two Study Group are listed in Appendix 1 in this article's Online Repository at www.jacionline.org.

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