Long-term outcomes of bronchial thermoplasty in subjects with severe asthma: a comparison of 3-year follow-up results from two prospective multicentre studies

Abstract

Bronchial thermoplasty is an endoscopic therapy for severe asthma. The previously reported, randomised sham-controlled AIR2 (Asthma Intervention Research 2) trial showed a significant reduction in severe asthma exacerbations, emergency department visits and hospitalisations after bronchial thermoplasty. More “real-world” clinical outcome data is needed.This article compares outcomes in bronchial thermoplasty subjects with 3 years of follow-up from the ongoing, post-market PAS2 (Post-FDA Approval Clinical Trial Evaluating Bronchial Thermoplasty in Severe Persistent Asthma) study with those from the AIR2 trial.279 subjects were treated with bronchial thermoplasty in the PAS2 study. We compared the first 190 PAS2 subjects with the 190 bronchial thermoplasty-treated subjects in the AIR2 trial at 3 years of follow-up. The PAS2 subjects were older (mean age 45.9 versus 40.7 years) and more obese (mean body mass index 32.5 versus 29.3 kg·m−2) and took higher doses of inhaled corticosteroids (mean dose 2301 versus 1961 μg·day−1). More PAS2 subjects had experienced severe exacerbations (74% versus 52%) and hospitalisations (15.3% versus 4.2%) in the 12 months prior to bronchial thermoplasty. At year 3 after bronchial thermoplasty, the percentage of PAS2 subjects with severe exacerbations, emergency department visits and hospitalisations significantly decreased by 45%, 55% and 40%, respectively, echoing the AIR2 results.The PAS2 study demonstrates similar improvements in asthma control after bronchial thermoplasty compared with the AIR2 trial despite enrolling subjects who may have had poorer asthma control.

How effective is bronchial thermoplasty for severe asthma in clinical practice?

“…Although important, the study by CHUPP et al [11] has some limitations. The criteria used to define a severe exacerbation in PAS2 and AIR2 were not identical.…”

“…Published information on the effectiveness of bronchial thermoplasty in clinical practice is limited to a few small case series from Australia, Canada, France, the UK and the USA (table 2) [12][13][14][15][16][17][18], and from a UK national registry [19]. In this issue of the European Respiratory Journal, CHUPP et al [11], describe the interim 3-year results of the Post-FDA Approval Clinical Trial Evaluating Bronchial Thermoplasty in Severe Persistent Asthma (PAS2) study, which is a prospective, open-label, multicentre, observational post-market study mandated by the FDA to evaluate the durability of the treatment effect, and the short and long-term efficacy and safety of the procedure. 284 participants were enrolled from 2011 at 27 centres in the USA (n=23) and Canada (n=4), of whom 279 subjects received at least one bronchial thermoplasty treatment.…”

“…For example, participants in the PAS2 study, compared with those recruited to the AIR2 clinical trial, were slightly older (age 45.9 versus 40.7 years), had a higher body mass index, had a higher proportion taking maintenance oral corticosteroids (18.9% versus 4.2%), had more subjects who experienced severe exacerbations (74% TABLE 1 Key exclusion criteria used in AIR2 trial of bronchial thermoplasty in asthma [5] Aged >65 years Chronic sinus disease Prebronchodilator FEV1 <60% predicted Four or more oral corticosteroid courses for asthma exacerbation within the past 12 months Three or more hospitalisations for asthma within the past 12 months Former smoker, if >10 pack-years total smoking history A history of intubation for asthma or ICU admission for asthma within the prior 24 months Taking maintenance oral corticosteroids >10 mg daily Similar key exclusion criteria were used in the PAS2 study [11], except for chronic sinus disease. FEV1: forced expiratory volume in 1 s; ICU: intensive care unit.…”

“…What are the clinical implications of the PAS2 study by CHUPP et al [11] and other observational studies for the use of bronchial thermoplasty in the management of patients with severe asthma in clinical practice [20,21]? Real-life patients treated with bronchial thermoplasty are more likely to have features of more severe disease than those treated in the AIR2 trial.…”

Diagnosis and Management of Asthma – The Swiss Guidelines

“…Quite recently, BT was found to lead to a persistent reduction in severe exacerbations (compared to sham-treated patients) up to 5 years with a 48% average DOI: 10.1159/000486797 decrease over 5 years in severe exacerbation event rates (events per patient per year) in BT-treated patients compared with the 12 months prior to BT treatment. The decrease in severe exacerbations in the BT-treated patients included a substantial reduction in the use of systemic corticosteroids associated with those exacerbations [95]. The effectiveness of this technique has been confirmed in randomized controlled trials and is now endorsed by several international guidelines, including the Global Initiative for Asthma (GINA) guideline [3].…”