Increased prevalence of allergic asthma over 20 years in northern Sweden

Background: During the second half of the 20th century the prevalence of asthma has increased. Results on asthma prevalence trends are lacking after 2010, especially regarding studies separating allergic asthma from non-allergic asthma. Aim: The aim of this study is to estimate prevalence trends of current asthma, both allergic and non-allergic, from 1996 to 2006 and further to 2016. Methods: Three cross-sectional samples from the same area of Sweden, 20-69 years, participated in population surveys with the same validated questionnaire in 1996 (n=7104 participants, 85% response rate), 2006 (n=6165, 77%) and 2016 (n=5466, 53%), respectively. There was no overlap between the three samples. Current asthma was defined as physician-diagnosed asthma with current symptoms common in asthma and/or asthma medication use. Results: The prevalence of current asthma increased from 8.4% in 1996 to 9.9% in 2006 and 10.9% in 2016 (p Conclusion: The prevalence of allergic asthma increased from 1996 to 2006 and further to 2016, while the prevalence of non-allergic asthma remained on a similar level. The prevalence of symptoms common in asthma decreased slightly or remained stable despite a substantial decrease in the prevalence of smoking.