Age is associated with asthma phenotypes

Background and objective: The relationship between age and asthma phenotypes is important as population is ageing, asthma is becoming common in older ages and recently developed treatments for asthma are guided by phenotypes. The aim of this study is to evaluate whether age is associated with specific asthma phenotypes. Methods: This is a cross-sectional study. We included subjects with asthma of varied degrees of severity. Subjects underwent spirometry, skin prick test to aeroallergens, answered the Asthma Control Questionnaire and had blood samples collected. We performed binary logistic regression analysis to evaluate whether age is associated with asthma phenotypes. Results: We enrolled 868 subjects. In comparison with subjects ≤ 40 years, older subjects had high odds of irreversible airway obstruction (from 41 to 64 years, OR: 1.83 (95% CI: 1.32–2.54); ≥65 years, OR: 3.45 (2.12–5.60)) and severe asthma phenotypes (from 41 to 64 years, OR: 3.23 (2.26–4.62); ≥65 years, OR: 4.55 (2.39–8.67)). Older subjects had low odds of atopic (from 41 to 64 years, OR: 0.56 (0.39–0.79); ≥65 years, OR: 0.47 (0.27–0.84)) and eosinophilic phenotypes (from 41 to 64 years, OR: 0.63 (0.46–0.84); ≥65 years, OR: 0.39 (0.24–0.64)). Conclusion: Older subjects with asthma have low odds of atopic and eosinophilic phenotypes, whereas they present high odds of irreversible airway obstruction and severe asthma.