Age-specific incidence of allergic and non-allergic asthma

• BMC Pulmonary Medicine
• Research article
• Open Access
• Open Peer Review

• Johanna Pakkasela, 
• Pinja Ilmarinen, 
• Jasmin Honkamäki, 
• Leena E. Tuomisto, 
• Heidi Andersén, 
• Päivi Piirilä, 
• Hanna Hisinger-Mölkänen, 
• Anssi Sovijärvi, 
• Helena Backman, 
• Bo Lundbäck, 
• Eva Rönmark, 
• Hannu Kankaanranta & 
• Lauri Lehtimäki 

BMC Pulmonary Medicine volume 20, Article number: 9 (2020) 

• details

Abstract

Background

Onset of allergic asthma has a strong association with childhood but only a few studies have analyzed incidence of asthma from childhood to late adulthood in relation to allergy. The purpose of the study was to assess age-specific incidence of allergic and non-allergic asthma.

Methods

Questionnaires were sent to 8000 randomly selected recipients aged 20–69 years in Finland in 2016. The response rate was 52.3% (n = 4173). The questionnaire included questions on e.g. atopic status, asthma and age at asthma diagnosis. Asthma was classified allergic if also a physician-diagnosed allergic rhinitis was reported.

Results

Incidence of new asthma diagnoses/1000 person-years
divided into allergic (subjects with allergic rhinitis)
and non-allergic (subjects without allergic rhinitis) cases
in different age groups

The prevalence of physician-diagnosed asthma and allergic rhinitis were 11.2 and 17.8%, respectively. Of the 445 responders with physician-diagnosed asthma, 52% were classified as allergic and 48% as non-allergic. Median ages at diagnosis of allergic and non-allergic asthma were 19 and 35 years, respectively. Among subjects with asthma diagnosis at ages 0–9, 10–19, 20–29, 30–39, 40–49, 50–59 and 60–69 years, 70, 62, 58, 53, 38, 19 and 33%, respectively, were allergic. For non-allergic asthma, the incidence rate was lowest in children and young adults (0.7/1000/year). It increased after middle age and was highest in older age groups (2.4/1000/year in 50–59 years old).

Conclusions

The incidence of allergic asthma is highest in early childhood and steadily decreases with advancing age, while the incidence of non-allergic asthma is low until it peaks in late adulthood. After approximately 40 years of age, most of the new cases of asthma are non-allergic.

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