Cluster analysis of cough variant asthma using FeNO

Background: Asthma is a heterogeneous inflammatory disorder with several different phenotypes, and cough variant asthma (CVA) is a form of asthma which presents mainly cough. Cluster analysis of CVA using FeNO has not been reported. Objective: We classified CVA phenotypes using cluster analysis including FeNO value. Methods: Patients with CVA were retrospectively recruited. Data were taken from medical records, and cluster analysis was performed on 223 subjects. Results: From the cluster dendrogram [Fig1], five clusters were identified [Fig2]. Patients with CVA were classified as Cluster 1: highly eosinophilic bronchitis group [high value of FeNO alone, n=25], Cluster 2: atopic group [high IgE alone, n=25], Cluster 3: non-atopic and non-eosinophilic group [n=105], Cluster 4: distal airway narrowing group [low Forced Expiratory Flow at 75% of FVC (V 25 ), n=23], and Cluster 5: severe atopic group [extreme high value of IgE and/or extreme high value of FeNO, n=45]. Discussion: At least 20 percent of patients with CVA could be diagnosed using FeNO. More than 10 percent of patients with CVA showed distal airway narrowing.