Factors influencing the responsiveness to inhaled glucocorticoids of patients with moderate-to-severe asthma.

Study Objectives: Inhaled glucocorticoids (GCs) are the most effective control therapy for asthma. Although the clinical effects of inhaled GCs vary, there are few data on the differences in the responsiveness of individuals to inhaled GCs. The purpose of this study was to identify those factors that are associated with responsiveness to high-dose inhaled GCs in patients with moderate-to-severe asthma.
Design: This study was a prospective analysis.
Setting: Outpatient clinics of tertiary hospitals.
Patients: Eighty-six adult outpatients with moderate-to-severe asthma.
Methods: Eighty-six patients with asthma who had initial FEV1 values of < 80% predicted after they had received inhaled GCs (fluticasone propionate, 1,000 microg/d) for 4 weeks. The primary end points were FEV1, FEV1/FVC ratio, forced expiratory flow (midexpiratory phase), and the score at presentation in the asthma-related quality-of-life questionnaire (AQLQ).
Results: The inhalation of GCs for 4 weeks had significant improvements in the FEV1% predicted and in the AQLQ score compared with the baseline values. Asthmatic patients with responses of > 12% (n = 46, 53.4%) in the change in FEV1 (deltaFEV1 = [FEV1 at 4 weeks--baseline FEV1]/baseline FEV1 x 100) also had significantly higher proportions of blood eosinophils and lower FEV1 values (in liters) prior to treatment. The change in FEV1 values correlated with the number of sputum eosinophils prior to GC inhalation (r = 0.242; p < 0.05) and correlated inversely with the FEV1 percent predicted values prior to GC inhalation (r = -0.462; p < 0.001).
Conclusion: The FEV1 percent predicted and the blood and sputum eosinophil levels prior to GC inhalation are associated with the responsiveness to inhaled GCs in patients with moderate-to-severe asthma.