Cluster analysis of patients with cough, mainly cough variant asthma, showing a good response to asthma therapy

Introduction: Cough variant asthma (CVA) and asthma account for a large proportion of patients with chronic cough. We used hierarchical cluster analysis (HCA) to characterize the phenotypes of patients with cough, mainly those with CVA, who showed a rapid response to asthma therapy, and sought to identify simple diagnostic markers. Methods: Patients who initially presented with cough as the main symptom were retrospectively enrolled. Those who were clinically diagnosed with asthma/CVA were selected and analyzed. HCA was performed and the patients were classified by phenotype. Results: HCA identified the five following phenotypes among the 221 participants: highly eosinophilic bronchitis [high fractional exhaled nitric oxide (FeNO) , n = 28]; atopic [high total serum IgE , n = 23]; non-atopic and non-eosinophilic [n = 104]; distal airway narrowing [low FEF75 (V ・ 25), n = 21] and severely atopic [extremely high total serum IgE and/or extreme high FeNO, n = 45]. No significant differences in long-term prognosis were found among the phenotypes. Discussion: Five phenotypes were identified among patients with cough who showed a rapid response to asthma treatment. Wheezing was observed in about 24% of patients, and abnormal FeNO or V ・ 25 levels in about 30%.