Predictive Factors of Response to Inhaled Corticosteroids in Newly Diagnosed Asthma: A Real-world Observational Study

Background: Asthma is characterized by chronic airway inflammation, and inhaled corticosteroids (ICSs) have been recommended as first-line treatment. However, response to ICS treatment is various, and the prediction of response to ICSs is still difficult, especially in individuals with newly diagnosed asthma.

Objective: To assess the clinical factors and biomarkers associated with response to ICSs in newly diagnosed asthma.

Methods: A total of 150 ICS-naive patients with newly diagnosed asthma in the allergy clinic of a single tertiary hospital in Korea from January 2014 to January 2019 were included in this study. All patients initially received moderate-dose ICSs and were treated for more than 1 year. We compared the clinical characteristics and parameters between patients with and without acute exacerbation (AE) during the study period.

Results: In this study, 99 patients had no AE (stable asthma group), and 51 patients presented with more than 1 AE (unstable asthma group). The mean (SD) blood eosinophil count (635.7 [780.3] × 10/μL vs 373.4 [266.8] × 10/μL, P = .003) and sputum eosinophil count (15.2% [23.9%] vs 8.3% [15.4%], P = .051) were higher and the sputum neutrophil count (42.9% [35.1%] vs 61.3% [35.1%], P = .057) was lower in the stable asthma group than in the unstable asthma group.

Conclusion: High blood and sputum eosinophil counts can predict a good response to ICS treatment in terms of prevention of AE in individuals with newly diagnosed asthma. The sputum neutrophil count may be an effective predictor of response to ICSs, even though additional studies must be conducted.