Post-approval study for bronchial thermoplasty (BT): Results to 2 years.

Document Type

Conference Proceeding

Publication Date


Publication Title

Am J Respir Crit Care Med


Bronchial thermoplasty (BT) is a non-pharmacologic, device-based treatment for subjects ≥18 years with severe persistent asthma not well controlled with inhaled corticosteroids (ICS) and long-acting beta-agonists (LABA). The “Post-FDA Approval Clinical Trial Evaluating BT in Severe Persistent Asthma” (PAS2 study) collects real-world data on subjects undergoing BT treatment with the Alair BT System. We report for the first time baseline and follow-up results for the primary and secondary endpoints to 2 years. Methods: The PAS2 study is a prospective, open-label, observational, multi-center trial at US and Canadian centers. Subjects 18-65 years taking ICS ≥1000μg/day (beclomethasone or equivalent) and LABA ≥80μg/day (salmeterol or equivalent) were enrolled. Additional inclusion criteria were: pre-bronchodilator FEV1 ≥60% predicted, non-smoker for ≥1 year (<10 pack/years if former smoker), ≥2 days with asthma symptoms in the last 4 weeks, AQLQ ≤6.25, and in the 12 months prior to BT treatment have ≤2 hospitalizations, ≤3 lower respiratory tract infections, and ≤3 severe exacerbations. Subjects diagnosed with other severe respiratory diseases were excluded. Baseline demographics, AQLQ, medication usage, FEV1 and FVC, medical history, comorbidities, and 12-month baseline recall data (severe exacerbations and healthcare utilization) were recorded. Following BT, severe exacerbations, hospitalization, and ER visits, as well as FEV1 and FVC, were evaluated for each subject at 1 and 2 years post-therapy. Results: Two-hundred eighty-four subjects were enrolled at 27 centers; 279 subjects had at least 1 of 3 BT procedures; 271 subjects had all 3 BT procedures. Subjects had mean age 45.7 years with 64.5% female and mean BMI 32.2kg/m2. Mean ICS dose was 2269μg/day, LABA dose was 74μg/day, and SABA dose was 2.35μg/day at baseline. Baseline mean AQLQ was 4.03 with a mean of 25.2 years since asthma diagnosis. In the 12 months prior to first BT procedure, 78% of subjects had at least one severe exacerbation (mean 1.6/subject), 16% had hospitalizations, and 29% had ER visits. In the first and second year of follow-up, 50.6% and 45.4% of subjects had severe exacerbations, respectively. Similarly, 14.4% and 12.7% of subjects had hospitalizations in the first and second year of follow-up, and 18.3% and 13.5% of subjects had ER visits in the first and second year of follow-up. Conclusion: The PAS2 study shows that compared to the year prior to BT treatment, in the 2 years after BT treatment study subjects experienced improved asthma control with respect to severe exacerbations, hospitalizations and ER visits. Funding: Boston Scientific.



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