Characteristics of the European Thoracic Society/American Thoracic Society severe asthma definition as a determinant of future use of biologics/bronchial thermoplasty

BACKGROUND: International guidelines define severe uncontrolled asthma. Biologics or bronchial thermoplasty (Bio/BT) are recommended for such patients. OBJECTIVES: To determine which definitions of severe uncontrolled asthma are associated with an additional Bio/BT treatment in patients with severe uncontrolled asthma. METHODS: Consecutive 107 asthmatics (including 15 patients for whom Bio/BT was introduced within 3 months after examination), classified as treatment step 4 according to the Global Initiative for Asthma 2015 guideline, were eligible for this analysis. Patients were assessed using the European Thoracic Society/American Thoracic Society (ERS/ATS) severe uncontrolled asthma guideline as defined by these 4 characteristics: poor control (ACT < 20), frequent exacerbations (≥2/yr), admissions (≥1/yr), and airflow limitation (forced expiratory volume in 1 second < 80% of predicted), along with comorbidities, and biomarkers, including blood granulocytes, fractional nitric oxide, and capsaicin cough reflex sensitivity (C-CS). These indices were compared between patients with and without Bio/BT introduction, and multivariate logistic regression analysis was performed to determine the association of the 4 definitions with treatment needs for Bio/BT. RESULTS: Patients who were introduced to Bio/BT had heightened C-CS, heavier smoking history, and a greater prevalence of diabetes mellitus than those without (p < 0.05). Poor asthma control (ACT < 20), frequent exacerbations (≥2/yr), and admissions (≥1/yr) were relevant to the future use of Bio/BT in the multivariate regression analysis. Type 2-related biomarkers including absolute eosinophil counts were higher in patients in the Bio introduction group than in the BT introduction group. Meanwhile, there was no significant difference of the 4 characteristics of severe uncontrolled asthma definition between patients in the Bio and those in the BT groups. CONCLUSION: Although multiple factors such as treatment cost and asthma phenotypes affect treatment decision-making, the definition of poor asthma control, frequent exacerbations and admission by the ERS/ATS guidelines were important factors for an additional intensive treatment for severe uncontrolled asthma. TRIAL REGISTRATION: UMIN Clinical Trials Registry: UMIN000024734