Assessment of Bronchodilator Responsiveness and Spirometric Patterns in Patients with Rhinitis and Suspected Asthma

Bronchodilation testing (BDT) is routinely used to assess reversibility of airflow limitation. For patients with rhinitis who report asthma-related symptoms but often show preserved spirometry, the clinical patterns associated with bronchodilator responsiveness (BDR) are less clearly described. Understanding these patterns may help clinicians interpret lung function in real-world practice.

We retrospectively analyzed 555 consecutive patients who underwent spirometry and BDT at a single tertiary allergy center. Data on clinical symptoms, allergic status, type-2 inflammatory markers, baseline spirometry results, and BDT outcomes were collected. Associations between symptoms, spirometric indices, and BDR were evaluated. Exploratory analyses examined the relationship between FEV₁ improvements below the conventional ≥12% criterion and asthma-related symptoms.

Among all participants, 71.9% had allergic rhinitis, and 88.6% reported asthma-related symptoms. BDR was observed across a wide range of baseline spirometry values; 47.2% of BDT-positive patients had FEV₁ ≥80% predicted. Small airway indices, especially FEF_{5 0} % predicted, were strongly associated with BDR. Wheezing and chest tightness demonstrated clearer physiological correlations than coughing alone did. FEV₁ improvements slightly below the conventional ≥12% bronchodilator threshold were also associated with asthma-related symptoms, although these findings were exploratory and not intended as diagnostic criteria.

In patients with rhinitis and suspected asthma, airflow variability may be present even when FEV₁ appears preserved. Small-airway parameters and symptom profiles offer a useful context for interpreting BDT results. Modest FEV₁ changes may be clinically relevant and warrant further prospective study. These findings may help clinicians judge when bronchodilation testing is informative during the routine evaluation of suspected airway disease.