Increased Cough Receptor Sensitivity to Capsaicin Predicts a Positive Bronchial Thermoplasty Response: A Single-center Retrospective Study

BACKGROUND: Bronchial thermoplasty (BT) is a novel bronchoscopic therapy for severe uncontrolled asthma unresponsive to standard pharmacological treatments, including inhaled corticosteroids and long-acting beta-2 agonists. Although several studies have shown that BT improves asthma control, the optimal predictors of BT response remain unknown. PATIENTS AND METHODS: We reviewed 10 consecutive asthma patients treated with BT at Kanazawa University Hospital between January 2016 and March 2018 and attempted to identify factors that correlated with a positive BT response. RESULTS: All patients had the most severe persistent asthma according to the 2017 Japanese guidelines for adult asthma and were uncontrolled despite adequate treatments including high-dose inhaled corticosteroids and long-acting beta-2 agonists. Six patients had significant improvement in asthma control evaluated with the Asthma Control Questionnaire-6. Eight patients showed a significant improvement in asthma-specific health-related quality of life evaluated with the Asthma Quality of Life Questionnaire. The number of severe asthma exacerbations decreased in 6 patients. The maintenance dose of oral corticosteroids decreased in 1 patient. There were no severe adverse events related to the procedure. Six patients showed a positive BT response, and all 4 patients with increased cough receptor sensitivity to capsaicin responded to BT. No other factors, including age, smoking status, body mass index, age of asthma onset, disease duration, blood eosinophil count, total serum immunoglobulin E, prebronchodilator forced expiratory volume in 1 second, reversibility to beta-2 agonist, or fractional exhaled nitric oxide, were associated with a positive BT response. CONCLUSION: Increased cough receptor sensitivity to capsaicin may predict a positive BT response.