Effectiveness and Safety of Bronchial Thermoplasty in the Treatment of Severe Asthma

Abstract

Journal. American J Respir Crit Care Medicine 2010; 181:116–124. Rationale. The treatment of severe asthma has been expanded with the introduction of a recent bronchoscopic procedure entitled bronchial thermoplasty in which controlled heat energy is impacted on the airway wall to produce a decline in smooth muscle. The objectives of the authors was to assess the effectiveness and safety of bronchial thermoplasty versus a sham protocol in individuals with severe asthma who continue to be symptomatic despite conventional therapy with high dose inhaled corticosteroids and long-acting beta agonists. Methods. A total of 288 adult with severe asthma using an intent to treat analysis were randomized to bronchial thermoplasty or sham control. Each subject was evaluated with three bronchoscopic procedures. The primary outcome was the difference in asthma quality-of-life questionnaire scores from baseline to average of 6, 9 and 12 months (integrated AQLQ). Adverse events and health care utilization were determined to evaluate safety. Statistical design and analysis of the primary endpoint was Bayesian. The target posterior probability of superiority of bronchial thermoplasty over sham was 95% except for the primary endpoint (96.4%). Results and outcomes. The amelioration from baseline in the integrated AQLQ score was superior in the bronchial thermoplastic group when compared with sham (bronchial thermoplasty 1.35 plus or −1.10; sham 1.16 plus or −1.23)(PPS, 96% intention to treat and 97.9% per protocol). 79% of the bronchial thermoplasty and 64% of sham subjects developed changes in the AQLQ of 0.5 or greater (PPS, 99.6%). Six percent more of bronchial thermoplasty individuals were hospitalized in the treatment period up to six weeks after bronchial thermoplasty. In the post therapy period, which was 6 to 52 weeks after bronchial thermoplasty, the bronchial thermoplasty group experienced fewer severe exacerbations, ER visits and absence from work or school when compared with the sham group (PPS 95.5, and 99.9 and 99.3% respectively). Conclusions of the authors. Bronchial thermoplasty in individuals with severe asthma ameliorates asthma specific quality of life with a decline in severe exacerbations, in health care utilization in the post treatment period. Reviewer's comments. The strengths of the study were the relatively large number of subjects as well as the multicenter, randomized, double blind with sham study design. The findings of the study hold that bronchial thermoplasty provides clinically significant amelioration of severe exacerbations requiring corticosteroids, ED visits and time lost from work and school during the post treatment therapy in individuals with severe asthma or those with inadequately controlled asthma, together with an improvement in quality of life. The authors conclude that increased risk of adverse events in the short-term after bronchial thermoplastic is outweighed by the benefits of bronchial thermoplastic that continues for at least one year. Bronchial thermoplasty provides a novel supplementary procedure that provides additional therapy beyond conventional utilization of high-dose inhaled steroids and long-acting beta agonist to decrease the morbidity from severe asthma. Further large prospective studies randomized with sham are needed to confirm the author's findings. An associated editorial in the same issue indicates that long-term clinical morphologic research in various severe asthma phenotypes is still needed to obtain required information for clinical decisions regarding this procedure.