Asthma increased in young adults from 2008–2016 despite stable allergic rhinitis and reduced smoking

BACKGROUND: Studies have produced inconsistent results on prevalence trends in asthma and allergic rhinitis (AR). We surveyed young adults about asthma in 2008 and 2016 and examined the impact of gender, AR and smoking. METHODS: Thirty-thousand randomly selected subjects aged 16–75 years in Western Sweden received postal questionnaires in 2008 and 50,000 in 2016. This study is based on responders aged 16–25 years, 2,143 in 2008 and 2,484 in 2016. RESULTS: From 2008–2016 current asthma increased from 9.3% to 11.5% (p = 0.014) and was significant in males without AR (aOR 1.83, 95% CI 1.09–3.07) and male smokers (aOR 3.02, 95% CI 1.12–8.13). In both years the risk of current asthma was reduced by growing up on a farm (aOR 0.26, 95% CI 0.81–0.84 and aOR 0.47, 95% CI 0.23–0.996), independent of a family history of asthma or allergy. AR did not differ significantly from 2008–2016 (22.5% vs 24.4%, p = 0.144). Current smoking decreased from 20.3% to 15.2% (p<0.001), especially in females (23.5% to 16.2%, p<0.001). Female smokers started smoking later and smoked fewer cigarettes in 2016 than 2008. In 2016, 4.8% of the cohort reported using electronic cigarettes. Of those, 60.7% also smoked tobacco and more than two-thirds who used both (67.2%) were heavy smokers. CONCLUSION: Current asthma increased in respondents aged 16–25 from 2008–2016, mainly among males without AR and male smokers. Current AR levelled off in this young population, while current smoking decreased among females.