Onset of allergic asthma has a strong association with childhood, but only a few studies have analyzed the relationship between the incidence of asthma from childhood to late adulthood and allergy.

A new study published in BMC Pulmonary Medicine assessed the age-specific incidence of allergic and non-allergic asthma.

Here, 8000 randomly selected patients from Finland, aged 20-69 years, completed questionnaires on the atopic status, asthma and age at asthma diagnosis; the response rate was 52.3% (n = 4173). Asthma was classified allergic if a physician-diagnosed allergic rhinitis was also reported.

The findings showed that 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% were found to be allergic, respectively. Meanwhile, for non-allergic asthma, the incidence rate was lowest in children and young adults—which increased after middle age and was highest in older age groups.

From the results, it was inferred that 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.