Allergic rhinitis phenotypes based on bronchial hyperreactivity to methacholine

Background: Allergic rhinitis (AR) and asthma may be associated, bronchial hyperreactivity (BHR) is quite common in AR patients. Methacholine (MCH) is a stimulus able to elicit BHR, as many other ones. Phenotyping AR is an up-to-date issue. Objective: The aim of this study was to evaluate whether MCH bronchial challenge is able to differentiate patients with AR. Methods: A total of 298 patients (277 males, mean age 28.9 years), suffering from AR were evaluated. Sensitization, rhinitis duration, values for bronchial function (forced vital capacity [FVC], forced expiratory volume [FEV](1), forced expiratory flow [FEF](25-75), and FEV1/FVC ratio), MCH bronchial challenge, visual analog scale (VAS) for nasal and bronchial symptoms perception, and fractioned exhaled nitric oxide (FeNO) were evaluated. Results: BHR-positive patients (22.8%) had significantly more frequent mite allergy (p = 0.025), longer AR duration (p < 0.001), lower FEV1 (p = 0.003), FEV1/FVC (p < 0.001), FEF25-75 (p < 0.001), higher (p < 0.001), and higher VAS values for both nasal and bronchial symptoms (p < 0.001 for both) in comparison with BHR-negative patients. FeNO can be considered a good predictor for BHR in AR patients (area under the curve, 0.90) with 27.0 ppb as cutoff. Conclusions: The present study demonstrates that BHR to MCH could define two distinct phenotypes in AR patients. It could be clinically relevant as BHR-positive patients have initial impairment of lung function, impaired FeNO values, and worsening of respiratory symptoms perception.