Abstract
Background: In 2005, smoking was banned in public places in Sweden.
Aim: To compare the prevalence of respiratory symptoms and asthma among adults in 1996 and 2006 by smoking habits.
Methods: In 1996, 7104 randomly selected subjects (response rate 85%) in Northern Sweden aged 20-69 answered a postal questionnaire including questions about respiratory diseases, symptoms and smoking habits. Correspondingly, in 2006 a new sample of 6165 subjects (77% responded) of same age answered the same questionnaire.
Results: All respiratory symptoms were strongly related to smoking. The prevalence of most respiratory symptoms decreased significantly from 1996 to 2006 parallel to a decrease in smoking, which decreased from 27 to19%. The prevalence of sputum production decreased from 19.1 to 15.0%, longstanding cough 12.4-10.8%, chronic bronchitis 7.4-6.3%, and recurrent wheeze 13.4-12.1%. The prevalence of these symptoms was similar among smokers, and decreased among non-smokers. Physician-diagnosed asthma increased among both smokers and non-smokers, totally from 9.3 to 11.5%. However, the proportion of medicine users and symptomatics among the asthmatics were lower in 2006. In multivariate analysis adjusted for confounders, a significant increase of asthma by study year was found (OR 1.4). Corresponding analysis for chronic bronchitis yielded a significant decreased effect by study year (OR 0.8).
Conclusions: The decreased prevalence of respiratory symptoms was parallel to a decrease in smoking. The decrease in bronchitis symptoms among non-smokers may be related to a reduction of environmental tobacco smoke and occupational airborne exposures. Increased diagnostic activity can explain the increase in asthma.
- © 2011 ERS