Introduction

The contribution of seasonal aeroallergens, particularly tree pollen, to asthma development in patients with allergic rhinitis remains unclear despite growing evidence linking upper and lower airway disease.

Aim

This study aimed to assess the association between tree pollen allergy and asthma and evaluate the impact of co-sensitisation patterns in patients with allergic rhinitis.

Material and methods

This retrospective cross-sectional study included 1100 adults with allergic rhinitis. Sensitisation to inhalant allergens, including tree pollen, grasses, weeds, and perennial allergens, was assessed using skin prick tests and/or serum allergen-specific IgE measurements. Asthma prevalence was compared between patients with and without tree pollen sensitisation. Multivariable logistic regression identified independent predictors of asthma.

Results

Sensitisation to at least one inhalant allergen was found in 1078 (97%) patients, including 254 (23.1%) patients sensitised to tree pollen. Asthma was more common in patients with a tree pollen allergy than in those without (41.3% vs. 25.9%, p = 4.7 × 10^-6), corresponding to an odds ratio (OR) of 2.02 (95% CI: 1.50–2.71). In multivariable analysis, tree pollen allergy remained independently associated with asthma (OR = 1.88; 95% CI: 1.36–2.58; p < 0.001), together with perennial allergen sensitisation (OR = 1.72; 95% CI: 1.31–2.25; p < 0.001). Among patients with a tree pollen allergy, concomitant perennial allergen sensitisation was the strongest predictor of asthma (OR = 2.05; 95% CI: 1.29–3.27; p = 0.002).

Conclusions

Tree pollen allergy is independently associated with asthma in allergic rhinitis patients, and coexisting perennial allergen sensitisation further increases asthma risk.