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

Abstract

@ERSpublications Bronchial thermoplasty can be effective in patients who often have features of more severe asthma than in AIR2 http://ow.ly/Qv5730cTIuBCite this article as: Thomson NC, Chanez P. How effective is bronchial thermoplasty for severe asthma in clinical practice? Eur Respir J 2017; 50: 1701140 [https://doi.org/10.1183/13993003.01140-2017.Bronchial thermoplasty is an intervention developed for the treatment of asthma through the delivery of radio frequency energy to the airways [1,2]. Evidence for the efficacy and safety of bronchial thermoplasty in severe asthma is based on the results of three randomised controlled trials [3][4][5]. Two trials compared bronchial thermoplasty with usual care, the Asthma Intervention Research (AIR) trial [3] and the Research in Severe Asthma (RISA) trial [4], whereas the third trial (AIR2) compared bronchial thermoplasty with a sham procedure [5]. The AIR2 trial reported improved asthma quality of life questionnaire (AQLQ) scores, reduced severe exacerbations and decreased emergency department visits in the post-bronchial thermoplasty treatment period [5]. Bronchial thermoplasty was associated with a short-term increase in asthma-related symptoms and hospital admissions for asthma during the treatment phase [3][4][5]. Follow-up observational studies to date support the long-term safety of the procedure, based on unchanged rates of respiratory adverse events, lung function, serial computed tomography scans and rates of hospital admissions or emergency department visits in years 2-5 following the AIR [6], RISA [7] and AIR2 trials [8]. A Cochrane systematic review of the trials concluded that there was a modest clinical benefit in asthma quality of life and a reduction in exacerbation rates 12 months after bronchial thermoplasty [9]. In 2010, the Food and Drug Administration (FDA) gave premarket approval for the Alair bronchial thermoplasty system (Boston Scientific, Marlborough, MA, USA) as a treatment for severe persistent asthma in patients 18 years and older whose asthma is not well controlled with inhaled corticosteroids and a long-acting β-agonist [10]. Bronchial thermoplasty is also approved for the treatment of asthma in the European Union and in many countries worldwide.

Measuring the effects of bronchial thermoplasty using oscillometry

“…Nevertheless, the data were prospectively collected and similar between two academic centres. Furthermore, the clinical benefit was sustained and similar to previous reports . Given the substantial sample size in the current study, the authors feel that it is unlikely that further studies using oscillometry will shed light on the effects of BT.…”

“…As has been observed in previous studies, spirometry did not change despite the demonstrated clinical improvement. Although the mechanisms have not been clearly defined, one suggestion is that BT might be inducing physiological changes in the small airways—the zone of the lung that is inadequately assessed by spirometry .…”

“…Bronchial thermoplasty (BT) is a novel endobronchial treatment using radiofrequency delivered to the large airways in patients with severe asthma . It has been demonstrated to reduce exacerbations and improve quality of life in three major randomized controlled trials and several real‐world studies . However, with the exception of the RISA study, no improvement has been demonstrated in spirometry.…”

Bronchodilator responsiveness as a predictor of success for bronchial thermoplasty

“…However, in most studies of BT, patients exhibit significant clinical improvement without any improvement in FEV 1. [17][18][19] This suggests that we may have been looking in the wrong place in attempting to understand how BT works. It is well established that spirometry predominantly measures airway resistance in the larger airways.…”

Asthma: A Loss of Post-natal Homeostatic Control of Airways Smooth Muscle With Regression Toward a Pre-natal State

“…Some have argued that ASM is simply a vestigial tissue with no significant function in highly evolved mammals (154,155). This argument was one of a number used to promote the concept of thermoplasty and muscle destruction as a potentially safe approach to the treatment of asthma (156)(157)(158).…”