In patients with more severely obstructed asthma with prebronchodilator forced expiratory volume in 1 second (FEV1) below 50% predicted, bronchial thermoplasty (BT) was safe and effective, with clinical indicators demonstrating efficacy similar to that seen in their less obstructed counterparts, according to study results published in Chest.
Most research on BT in asthma has focused on individuals who are less obstructed (FEV1 >50%), with limited data available on BT in patients who are more severely obstructed (FEV1 <50%). Consequently, patients with more significant disease are often excluded from this therapeutic option. The investigators sought to compare BT safety and efficacy in 2 asthma subpopulations of patients who were more vs less obstructed, hypothesizing that patients with more serious disease would still benefit.
Between June 2014 and December 2018, 70 consecutive patients with severe asthma were recruited from the Australian BT Registry, with 68 (mean age, 57.8 years; 58.8% women) included in the final prospective analysis. Patients were divided into 2 groups, according to baseline prebronchodilator FEV1: <50% (group 1) or ≥50% (group 2) predicted.
The safety outcomes were adverse events (AEs) comprising a hospital stay >24 hours planned or any emergency department visit or hospital readmission within 30 days of discharge. The primary efficacy outcome was the change from baseline on the Asthma Control Questionnaire (ACQ) score at 6 months post-BT; 6-month secondary outcomes included exacerbation frequency, medication changes and FEV1%.
At baseline, group 1 (n=32; mean age, 61.3 years; 47% men) had a mean ACQ score of 3.1, with an FEV1 of 40.2% predicted and a mean daily dose of 7.6 mg of oral corticosteroids (OCS). Group 2 (n=36; mean age, 57.4 years; 36% men) had a mean ACQ score of 3.3, with an FEV1 of 71.4% predicted and a 5.9 mg mean daily OCS dose.
Based on a minimal clinically significant ACQ change of 0.5, there were 59 (86.7%) total responders (86.7%) in both cohorts. Both groups saw similar significant improvements in ACQ scores, exacerbation frequencies, OCS weaning rates, and reductions in the use of reliever medications (P <.001 for all). There were no significant differences in efficacy measures between the groups (P >.05 for all).
There was no increase in AE incidence in group 1 compared with group 2, which saw AE rates of 6.25% and 12.0%, respectively. All patients recovered completely from their respective AEs, and there were no deaths reported during follow-up.
“This study demonstrates that BT can confidently be offered to asthmatic patients with an FEV1 30-50% predicted without risk of more frequent or more severe adverse events, and with the expectation of the same degree of response as patients with better lung function,” noted the investigators.
Disclosures: The authors wish to thank Peninsula Health and Monash University for their support-in-kind for this project.
No author has any conflict of interest in relation to this work.
Langton D, Ing A, Fielding D, et al. Safety and effectiveness of bronchial thermoplasty when FEV1 less than 50% [published online September 13, 2019]. Chest. doi:10.1016/j.chest.2019.08.2193