Childhood and onset of allergic asthma are strongly associated, but only a few studies have analyzed incidence of asthma from childhood to late adulthood in relation to allergy. Researchers found 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.
Questionnaires were sent to randomly selected recipients aged 20-69 years. The questionnaire included questions on atopic status, asthma, and age at asthma diagnosis. Asthma was classified allergic if also a physician-diagnosed allergic rhinitis was reported.
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. It increased after middle age and was highest in older age groups.
Pakkasela J, Ilmarinen P, Honkamäki J, Tuomisto LE, Andersén H, Piirilä P, Hisinger-Mölkänen H, Sovijärvi A, Backman H, Lundbäck B, Rönmark E, Kankaanranta H, Lehtimäki L. Age-specific incidence of allergic and non-allergic asthma. BMC Pulm Med. 2020 Jan 10;20(1):9. doi: 10.1186/s12890-019-1040-2. PMID: 31924190; PMCID: PMC6954552.