Predicting the Response to Bronchial Thermoplasty

Abstract

Although it is established that not all patients respond to bronchial thermoplasty (BT), the factors that predict response/nonresponse are largely unknown. To identify baseline factors that predict clinical response. The records of 77 consecutive patients entered into the Australian Bronchial Thermoplasty Registry were examined for baseline clinical characteristics, and outcomes measured at6and 12 months after BT, such as change in the Asthma ControlQuestionnaire (ACQ) score, exacerbation frequency, the requirement for short-acting beta-2 agonist (SABA) medication and oral corticosteroids, and improvement in spirometry. 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. 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 inFEV1 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 10puffs/d of SABA experienced the greatest reduction in SABA requirement (-12.4 ± 10.5 puffs, P < .001). The most severely afflicted patients had the greatest improvements in ACQ score, exacerbation frequency, and medication requirement.