Accuracy and Safety of Nasal Allergen Challenge in Asthmatic and Non-Asthmatic Patients

Nasal allergen challenge (NAC) is the gold standard for the diagnosis of allergic rhinitis (AR) phenotypes. However, studies on its diagnostic reliability and safety in rhinitis patients with- and without-asthma are scarce. Our aim was to analyse the accuracy and safety of NAC in asthmatic and non-asthmatic rhinitis patients. We retrospectively evaluated NAC performed in AR, local allergic rhinitis (LAR), non-allergic rhinitis (NAR) patients, and controls monitored by total nasal-ocular symptoms label-score (TNOSS) and percentage of change in volume 2-6cm in acoustic rhinometry (Δvol2-6cm). The accuracy of NAC, and optimum cut-off points of TNOSS and Δvol2-6cm were calculated by receiver operating characteristic (ROC) curves. Safety was explored by the registration of adverse events (AE) in asthmatic and non-asthmatic patients. Two methods of allergen application (nasal spray vs micropipette) and protocols of NAC with a single or multiple allergens (NAC-S vs NAC-M) were compared. We evaluated 11499 NAC performed in 6348 subjects (96% patients and 4% controls). The optimum cut-off points were Δvol2-6cm≥25% (AR and LAR: sensitivity 99%, specificity 100%, PPV 100%, NPV 98%), and TNOSS≥4 for AR (sensitivity 69%, specificity 90%, PPV 90%, NPV 96%) and LAR (sensitivity 55%, specificity 90%, PPV 90%, NPV 55%). No bronchial or systemic AE occurred. Four patients (1 asthmatic and 3 non-asthmatics) had a mild-moderate local oropharynx AE, with normal auscultation and spirometry. Nasal allergen challenge is a high accuracy and safety diagnostic test in asthmatic- and non-asthmatic rhinitis patients that can be used in clinical practise.