Bronchial thermoplasty: Long-term safety and effectiveness in patients with severe persistent asthma

Abstract

Background Bronchial thermoplasty (BT) has previously been shown to improve asthma control out to 2 years in patients with severe persistent asthma. Objective To assess effectiveness and safety of BT in asthma patients 5 years post therapy. Methods BT-treated subjects from the Asthma Intervention Research 2 (AIR2) Trial (ClinicalTrials.gov NCT01350414) were evaluated annually for 5 years to assess long-term safety of BT and durability of treatment effect. Outcomes assessed post-BT included severe exacerbations, adverse events, healthcare utilization, spirometry data, and high resolution computed tomography (HRCT) scans. Results 162/190 BT-treated subjects (85.3%) from the AIR2 Trial completed 5 years of follow-up. The proportion of subjects experiencing severe exacerbations and Emergency Room visits, and the rates of events in each of years 1 to 5 remained low and were less than those observed in the 12 months prior to BT treatment (average 5 year reduction in proportions: 44% for exacerbations and 78% for ER visits). Respiratory adverse events and respiratory-related hospitalizations remained unchanged in Years 2 through 5 as compared to the first year after BT. Pre-BD FEV1 values remained stable between years 1 and 5 after BT, despite a 17% reduction in average daily inhaled corticosteroid dose. HRCT scans from baseline to 5 years after BT showed no structural abnormalities that could be attributed to BT. Conclusions These data demonstrate the 5-year durability of the benefits of BT with regard to both asthma control (based on maintained reduction in severe exacerbations and ER visits for respiratory symptoms) and safety. BT has become an important addition to our treatment armamentarium and should be considered for patients with severe persistent asthma who remain symptomatic despite taking ICS (inhaled corticosteroids) and LABA (long-acting-β2-agonists).

Airway Inflammation after Bronchial Thermoplasty for Severe Asthma

“…Previous human studies of BT have proven the safety and long-term efficacy of BT on patients with both mild and severe asthma (17)(18)(19)(20)(21)(22)(23). However, sustained improvement in pulmonary function, as measured by FEV 1 or FVC, generally has not been demonstrated after BT in these studies.…”

“…BT is delivered in three sessions each separated by 3 weeks. The benefits of BT as demonstrated in clinical trials include reduced asthma symptoms, fewer acute exacerbations, and improved quality of life (16)(17)(18)(19)(20)(21)(22)(23). The mechanism is believed to be radioablation of airway smooth muscle mass within the central airways with consequent reduction in bronchial reactivity (19,20).…”

Recommendations for the use of bronchial thermoplasty in the management of severe asthma

“…The clinical effectiveness of BT has been confirmed in two prospective cohort feasibility studies, [14,22] three randomised controlled trials (RCTs), [23][24][25] one of which was published in the New England Journal of Medicine, and three prospective cohort followup studies interrogating long-term outcomes and safety [26][27][28] (the relevant studies are summarised in Table 1). The AIR trial enrolled 112 patients with moderate to severe asthma (FEV 1 60 -85% of predicted).…”

“…The long-term safety of BT (up to 5 years) has been demonstrated in three studies. [26][27][28] There is no consistent evidence that BT is causally associated with bronchial stenosis or bronchiectasis. In the AIR2 follow-up study, only three of 93 patients developed new (n=1) or worsening bronchiectasis (n=2) as shown on HRCT; it remains unclear whether this was a complication of asthma or related to BT.…”

“…[27,28] A follow-up of the RISA cohort demonstrated that the reductions in hospitalisations (70% reduction) and ER visits (~66% reduction) were sustained for 5 years. [27] There was no long-term change in the predicted FEV 1 .…”