Allergic Rhinitis Phenotypes Based on Bronchial Hyperreactivity to Methacholine

Abstract

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 FEV 1 /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 FEV 1 ( 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, a worsening of respiratory symptoms perception.