Prevalence of asthma in Portugal - The Portuguese National Asthma Survey

A 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.Data 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).Current 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.Asthma is a chronic inflammatory disease of the airways associated with episodes of wheezing, chest tightness, shortness of breath and cough especially at night [1]. Epidemiological studies at a population level are crucial for the assessment of population needs related to chronic respiratory diseases, the baseline to define health policies [2]. However few data on asthma prevalence are available in Portugal and, as most of the studies use non-standardized methods, prevalence estimates are difficult to compare. Standardized methodology on asthma symptoms prevalence is limited for ages between 20–44？years old in European Community Respiratory Health Survey (ECRHS) [3] and 6–7 and 13–14？years old in International Study of Asthma and Allergies in Childhood (ISAAC) [4]. In Portugal, both surveys were conducted in a small number of cities [5,6].