[European Community Respiratory Health Survey: The main results so far with special reference to Iceland.].

Introduction: The European Community Respiratory Health Survey (ECRHS) was the first project embarked on extensive study of geographical difference between countries with regards to asthma and atopy incidence in a young adult population. The same methodology and definitions were used at all study sites. The purpose of this article is to review the published results of the ECRHS with a special emphasis on the findings from the Icelandic population, and compare these results with those from the participants from the other nations and study sites.

Methods: Compiled results from all study sites participating in the ECHRS hereto published were reviewed. The compiled data are derived from approximately 140.000 individuals aged 20-44 (birth-years 1946-71) from 22 nations and 48 study sites. The Icelandic population was chosen from the greater Reykjavik metropolitan area. Subjects responded to seven questions on respiratory symptoms, diagnosis of asthma and use of asthma medications. In the latter part of the investigation, 800 individuals were randomly selected from each study site. They were asked to respond to a detailed questionnaire. Subsequently spirometry, methacholine challange and skin prick testing to 11-12 common aeroallergens was performed. Additionally, allergen specific IgE and total IgE was measured. Somewhat fewer sites participated in this latter part: 17 nations and 37 study sites.

Results: The findings are presented from two angles: the compiled data from all study sites and the results from the Icelandic population; specifically comparing the Icelandic data with the participants from the other nations. The study showed a geographical difference in the incidence of asthma, bronchial hyper- responsiveness and other respiratory symptoms. In the first part of the study, an eight-fold difference in wheezing, six-fold difference in asthma, ten-fold difference in physician- diagnosed asthma and a four-fold difference in the prevalence of allergic rhinitis was found between the study sites. "English-speaking" nations had the highest prevalence of respiratory diseases and Iceland, Spain, Germany, Italy, Algeria and India had the lowest incidence. A three-fold difference in the prevalence of allergy and an eight-fold difference in bronchial responsiveness were found between study sites in the latter part of the study. The incidence of asthma was highest in the lower age groups. Atopy prevalence (defined as a positive specific IgE for at least one allergen) was highest in Australia. Other English speaking nations and Switzerland had prevalence over 40%. Iceland had the lowest prevalence of atopy (23.6%) and Greece, Norway and Italy all had a prevalence of atopy under 30%. Total IgE was highest in Greece, France, Ireland and Italy (>50kU/L), but was lowest in Iceland (13.2 kU/L). The article speculates on the possible effects of the environment on the prevalence of wheezing, bronchial reactivity and atopy in the different study sites.

Summary: RESULTS from the European Community Respiratory Health Survey demonstrate a substantial difference in the prevalence of asthma, bronchial responsiveness and atopy between study sites. The prevalence was highest in countries where English is the native language. Of all study sites, the prevalence was lowest in Iceland. In the articles, possible explanations for this discrepancy are reviewed.