Age of onset of asthma influences the severity of asthma and defines the prevalence of comorbid conditions, according to a retrospective global study of data from five European countries published in the Journal of Allergy and Clinical Immunology: In Practice

Baan et al examined national electronic health records databases from the United Kingdom, Italy, Spain, Denmark and The Netherlands to study the differences in asthma, if any, as per age of onset. For this, they formed a study group of 586,436 adults with bronchial asthma and categorized them into three groups based on the age of onset of their disease; 81,691 had childhood-onset asthma (< 18 years), 218,184 adult-onset (between 18 and 40 years) and 286,561 late-onset asthma (>40 years). Among those with childhood-onset asthma, 45% were female, whereas they constituted 60% of the patients with late-onset asthma.

Overall, 42,611 patients (7.3%) had severe asthma. The prevalence of severe asthma was higher in patients with late-onset asthma (10%) with adjusted odds ratio of 2.8 followed by those with adult-onset asthma (5%) and childhood-onset asthma (3%). Similarly, the prevalence of uncontrolled asthma was higher in patient with late-onset asthma compared to adult-onset asthma and childhood-onset asthma; 8%, 6% and 0.4%, respectively.

Atopic disorders (31%) and overweight/obesity (50%) were the most frequently occurring comorbid conditions.

Patients with late-onset and adult-onset asthma were more likely to be overweight or obese compared to those with childhood asthma. The prevalence of overweight/obesity increased as the age of diagnosis increased; 30% in childhood asthma, 43% in adult-onset asthma and 61% in late-onset asthma. The prevalence of atopic disorders was reversed; lowest (25%) in late-onset asthma group vs 35% in adult-onset asthma; at 45%, it was highest in patients with childhood asthma.

The odds of nasal polyposis were higher in patients with late-onset asthma (adjusted OR 1.8). More patients in the late-onset category were diabetic (ORadj 2.3) and had gastroesophageal reflux disease (GERD) (ORadj 1.4).

This study has characterized asthma into three phenotypes and has shown differences in comorbidities according to the age of onset of asthma. Adult-onset and late-onset asthma was more common in women, while childhood-onset asthma was more prevalent in men. Patients who were diagnosed with asthma at a later age “late-onset asthma” were more likely to have severe and uncontrolled disease with frequent exacerbations and need for hospitalizations. Nasal pathologies (nasal polyps and chronic rhinosinusitis) were more associated with severe asthma. Allergic disorders were more common in patients with childhood onset of asthma.

History taking is an art that is fundamental to the practice of clinical medicine. A carefully elicited history provides useful clues to clinical decision making. This study also emphasizes the importance  of detailed history taking as a guide to managing the individual patient. Clinicians should be aware of the differences in the prevalence of comorbidities across the three phenotypes. “The age of asthma onset should be considered when assessing asthma control and asthma management”, suggest the authors.

Today is World Asthma Day and the theme for this year is “Closing Gaps in Asthma Care”. According to GINA, there exists a gap “between scientific evidence and actual delivery of care for people with asthma”. This study is a small step towards bridging this gap by translating knowledge to action.

Reference

1. Baan EJ, et al. Characterization of asthma by age of onset; a multi-database cohort study. J Allergy Clin Immunol Pract. 2022 Apr 7;S2213-2198(22)00330-0. doi: 10.1016/j.jaip.2022.03.019.