Abstract
Bronchial thermoplasty (BT) is a treatment for patients with poorly controlled, severe asthma. However, predictors of treatment response to BT are poorly defined.
Are there baseline radiographic and clinical characteristics that predict response to BT?
We conducted a longitudinal prospective cohort study of participants with severe asthma receiving BT across 8 academic medical centers. Participants received 3 separate BT treatments and were monitored at 3-month intervals for 1 year following BT. Similar to prior studies, a positive response to BT was defined as either improvement in Asthma Control Test (ACT) of ≥3 or Asthma Quality of Life Questionnaire (AQLQ) of ≥0.5. Regression analyses were utilized to evaluate the association between pre-treatment clinical and quantitative CT (qCT) measures with subsequent BT response.
From 2006 to 2017, 88 participants received BT with 70 (79.5%) identified as responders by ACT or AQLQ criteria. Responders were less likely to have an asthma-related ICU admissions in the prior year (3% vs 25%, P=0.01). On baseline qCT, BT responders had less air trapping percentage (odds ratio [OR] = 0.90, 95% confidence interval [CI] 0.82 to 0.99, P=0.03), a greater Jacobian determinant (OR = 1.49, 95% CI 1.05 to 2.11), greater standard deviation (SD) of the Jacobian determinant (OR = 1.84, 95% CI 1.04 to 3.26), and greater anisotropic deformation index (OR = 3.06, 95% CI 1.06 to 8.86]).
To our knowledge, this is the largest study to evaluate baseline qCT and clinical characteristics associated with BT response. Our results show that preservation of normal lung expansion, indicated by less air trapping, a greater magnitude of isotropic expansion, and greater within-lung spatial variation on qCT were predictors of future BT response.