Infections and atopy: An exploratory study for a meta-analysis of the "hygiene hypothesis"

G. Randi, A. Altieri, L. Chatenoud, F. Chiaffarino, C. La Vecchia

Research output: Contribution to journalArticlepeer-review


Background: According to the "hygiene hypothesis" selected allergic diseases could be prevented by exposure to infectious agents during early childhood. Methods: This study was performed to assess the feasibility of a future meta-analysis on the "hygiene hypothesis" and atopic diseases. Differences concerning the potential association with a history of infectious events, in terms of magnitude and homogeneity of global risk estimates between the three major atopic diseases (i.e. atopic dermatitis, asthma and allergic rhinitis) were examined. We conducted a preliminary analysis on a sample of articles published on this topic and cited in a recent and authoritative review. Results: The ranges of relative risks estimates (between 0.6 and 0.8) were similar for atopic dermatitis, allergic rhinitis and asthma. Compared with asthma and allergic rhinitis, reported global risk estimates were more stable for atopic dermatitis (lowest heterogeneity). Our analysis suggests that three main categories of indirect markers of exposure to infection can be identified: 1) geographical gradient, 2) indices of potential contact with infectious agents (such as number of siblings) and 3) history of infectious events. Conclusions: In this exploratory study, we chose articles cited in a single review and obtained a preliminary quantification of the association between infections and atopic diseases. The association with indirect markers of infection corresponded to 20% protection for atopic dermatitis, 30% for allergic rhinitis and 40% for asthma. In a subsequent meta-analysis, diseases should be considered separately and differences between types of exposures should be taken into account as one of the major end-points, with attention to time since exposure and disease onset.

Original languageEnglish
Pages (from-to)565-574
Number of pages10
JournalRevue d'Epidemiologie et de Sante Publique
Issue number6
Publication statusPublished - Dec 2004


  • Allergic rhinitis
  • Asthma
  • Atopic dermatitis
  • Atopy
  • Infections
  • Meta-analysis

ASJC Scopus subject areas

  • Public Health, Environmental and Occupational Health


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