Geographical variation in the prevalence of self-reported asthma was observed across Europe, but overall, self-reported asthma was more common in young adults, women and smokers. In all age groups, men and women, and irrespective of smoking behaviour, asthma was also associated with CRS.

Geographical variation in the prevalence of skin prick test positivity in Europe is unlikely to be explained by geographical variation in gender, age, smoking history, farm exposure, family size and BMI. Higher prevalence in younger, compared to older, adults may reflect cohort-associated increases in sensitization or the influence of ageing on immune or tissue responses.

Asthma is a common chronic disorder which may be increasing in prevalence. However, little is known of its distribution and determinants. The European Community Respiratory Health Survey (ECRHS) is a multicentre survey of the prevalence, determinants and management of asthma. This paper presents a descriptive account of the variation in self-reported attacks of asthma and asthma symptoms across Europe, and in part fulfils the first aim of the study. A screening questionnaire, including seven questions relating to the 12 month prevalence of symptoms of asthma, was distributed to representative samples of 20-44 year old men and women in 48 centers, predominantly in Western Europe. The median response rate to the questionnaire was 75% but, after removing from the denominator those who were the wrong age, were known to have moved out of the area, or had died, it was 78% (range 54-100). The prevalence of all symptoms varied widely. Although these were generally lower in northern, central and southern Europe and higher in the British Isles, New Zealand, Australia and the United States, there were wide variations even within some countries. Centres with a high prevalence of self-reported attacks of asthma also reported high prevalences of nasal allergies and of waking at night with breathlessness. The use of asthma medication was more common where wheeze and asthma attacks were more frequent. In most centres in The Netherlands, Sweden, New Zealand and the United Kingdom over 80% of those with a diagnosis of asthma were currently using asthma medication. In Italy, France and Spain the rate was generally less than 70%. These data are the best evidence to date that geographical differences in asthma prevalence exist, are substantial and are not an artefact of the use of noncomparable methods.

BackgroundAsthma is a frequent chronic respiratory disease in both children and adults. However, few data on asthma prevalence are available in Portugal. The Portuguese National Asthma Survey is the first nationwide study that uses standardized methods. We aimed to estimate the prevalence of current asthma in the Portuguese population and to assess the association between ‘Current asthma’ and comorbidities such as upper airways disease.MethodsA cross-sectional, population-based, telephone interview survey including all municipalities of Portugal was undertaken. Participants were randomly selected to answer a questionnaire based on the Portuguese version of the GA2LEN survey. ‘Current asthma’ was defined as self-reported lifetime asthma and at least one of 3 symptoms in the last 12 months: wheezing, waking with breathlessness or having an asthma attack.ResultsData were obtained for 6 003 respondents, with mean age of 38.9 (95%CI 38.2-39.6) years and 57.3% females. In the Portuguese population, the prevalence of ‘Current asthma’ was 6.8% (95%CI 6.0-7.7) and of ‘Lifetime asthma’ was 10.5% (95%CI 9.5-11.6) Using GA2LEN definition for asthma, our prevalence estimate was 7.8% (95%CI 7.0-8.8). Rhinitis had a strong association with asthma (Adjusted OR 3.87, 95%CI 2.90-5.18) and the association between upper airway diseases and asthma was stronger in patients with both rhinitis and sinusitis (Adjusted OR 13.93, 95%CI 6.60-29.44).ConclusionsCurrent asthma affects 695 000 Portuguese, with a prevalence of 6.8%. People who reported both rhinitis and sinusitis had the highest risk of having asthma.

This study does not support a role for selenium in protection against asthma, but effect modification and confounding cannot be ruled out.