Time trends of asthma in children – true increase or increased diagnostics?

Abstract

<b>Background:</b> Physician-diagnosis of asthma is still increasing but it is unknown if it is due to a true increase in morbidity or increased diagnostics. <b>Aim:</b> To study prevalence trends of asthma diagnosis and the association with morbidity indicators, i.e. symptoms, use of medication and severity among 8-year-old children from 1996 to 2017. <b>Methods:</b> The Obstructive Lung Disease in Northern Sweden (OLIN) studies have studied three pediatric cohorts using identical methods in 1996, 2006 and 2017 respectively. All children in 1st and 2nd grade (median age 8y) in three towns were invited to a parental questionnaire, completed by n=3430 in 1996 (97% participation), n=2585 in 2006 (96%), and n=2785 in 2017 (91%). <b>Results:</b> The prevalence of wheeze did not differ between the years: 10.1% in 1996; 10.8% in 2006; and 10.3% in 2017, p=0.621, while physician-diagnosed asthma increased: 5.7%, 7.4% and 12.2%, p&lt;0.001. The use of asthma medication in the last 12 months increased: 7.1%, 8.7% and 11.5%, p&lt;0.001. An increase was also seen in the proportion of children with physician-diagnosed asthma that neither reported wheeze nor use of asthma medication in the last 12 months: 8.6%, 18.8% and 30.0% (p&lt;0.001). Furthermore, the prevalence of severe asthma disease and the impact of asthma on daily activities decreased among children with physician-diagnosed asthma. <b>Conclusion:</b> The prevalence of wheeze was stable in 8-year-olds in this area from 1996 to 2017, while the prevalence of physician-diagnosed asthma simultaneously doubled. Our findings indicate that the increasing prevalence of asthma partially could be explained by changes in diagnostics, particularly among those with a less severe disease.