Correlation of Activation Site and Number with the Clinical Response to Bronchial Thermoplasty

OBJECTIVE: To investigate the relation of activation site and number with clinical response to bronchial thermoplasty (BT) in refractory asthma patients. METHODS: This work included 106 consecutive refractory asthma patients completing three BT sessions in our hospital from May 2016 to May 2019. Procedure details included recording delivery sites and those in BT. Asthma Control Questionnaire (ACQ) scores and spirometric measurements were recorded 1-day before treatment and 6 months post-treatment to explore the effects of BT activation number and site on clinical response. RESULTS: ACQ score (3.19±1.14 vs 1.26±0.63), forced expiratory volume in 1 sec (FEV1)% predicted (55.53±21.66 vs 66.19±22.50), FEV1 (1.53±0.74 vs 1.93±0.82), and forced vital capacity (FVC) (2.49±0.86 vs 2.92±0.94) significantly increased after three BT sessions compared with pre-session. Major bronchial ablation did not significantly improve BT response in asthma patients. Multivariate logistic regression identified baseline ACQ score and baseline FEV1% predicted as independent factors affecting the clinical response to BT. Correlation and regression analysis revealed a significant linear relationship between baseline ACQ and ACQ improvement, as well as a linear relationship between the third session activation number and ACQ improvement. Based on subgroup analysis of activation number, cohort C (activations ≥ 200) had better lung function, lower non-responding rate, and better long-term effectiveness than the other two cohorts. The activation number in the third BT session showed the strongest predictive ability compared with the first two sessions. CONCLUSION: Main bronchial ablation did not markedly affect clinical response to BT. Baseline ACQ and baseline FEV1% predicted were independent factors affecting clinical response to BT. Increasing the activation number might promote the therapeutic efficacy of BT, and the activation number in the third BT session correlated with and predicted the BT response.