Prevalence of airflow obstruction in smokers and never smokers in Switzerland

We aimed to measure age-specific prevalence of airflow obstruction (AO) in Switzerland in smokers and never smokers using pulmonary function tests and respiratory symptoms from 6126 subjects participating in the Swiss Cohort Study on Air Pollution and Lung Diseases in Adults.The lower limit of normal of FEV1/FVC ratio was used to define AO. Severity of AO was graded according to the recommendations of the Global Initiative for Chronic Obstructive Lung Disease.Prevalence of AO ranged from 2.5% in subjects aged 30-39 to 8.0% in those aged 70 or more. In multivariate analysis, age (ORaged70+ vs aged 30-39 2.8), smoking (OR 1.8) and asthma, (OR 6.7) were associated with AO. Never smokers constituted 29.3 % of subjects with AO. Never smokers with AO were younger, male and reported more frequently asthma than obstructive smokers. Obstructive smokers and never smokers had similar level of symptoms and quality of life impairment.Prevalence of AO in Switzerland is similar in magnitude compared to other developed countries. Never smokers account for a third of the prevalence which is higher than elsewhere. AO in never smokers deserve attention because of its frequency and its similar health impact than in smokers