Predicting the response to bronchial thermoplasty

Background: Although it is established that not all patients respond to bronchial thermoplasty (BT), the factors that predict response/nonresponse are largely unknown. Objectives: To identify baseline factors that predict clinical response. Methods: The records of 77 consecutive patients entered into the Australian Bronchial Thermoplasty Registry were examined for baseline clinical characteristics, and outcomes measured at 6 and 12 months after BT, such as change in the Asthma Control Questionnaire (ACQ) score, exacerbation frequency, the requirement for short-acting beta-2 agonist (SABA) medication and oral corticosteroids, and improvement in spirometry. Results: This was a cohort of patients with severe asthma: aged 57.7 ± 11.4 years, 57.1% females, 53.2% of patients taking maintenance oral steroids, 43% having been treated with an mAb, mean FEV₁ of 55.8% ± 19.8% predicted. Results: BT resulted in an improvement in the ACQ score from 3.2 ± 1.0 at baseline to 1.6 ± 1.1 at 6 months (P <.001). Exacerbation frequency in the previous 6 months reduced from 3.7 ± 3.3 to 0.7 ± 1.2 (P <.001). SABA requirement reduced from 9.3 ± 7.1 puffs/d to 3.5 ± 6.0 (P <.001), and 48.8% of patients were weaned completely off oral steroids. A significant improvement in FEV₁ was observed. Using multiple linear regression models, baseline ACQ score strongly predicted improvement in ACQ score (P <.001). Patients with an exacerbation frequency greater than twice in the previous 6 months showed the greatest reduction in exacerbations (−5.3 ± 2.8; P <.001). Patients using more than 10 puffs/d of SABA experienced the greatest reduction in SABA requirement (−12.4 ± 10.5 puffs, P <.001). Conclusions: The most severely afflicted patients had the greatest improvements in ACQ score, exacerbation frequency, and medication requirement.