Objectives

To evaluate potential biomarkers of predicting short-term (6-week) response to inhaled corticosteroid with subsequent evaluation of responders and nonresponders to asthma control over a longer interval (16 additional weeks).

Background

Inhaled corticosteroids (ICSs) are the preferred anti-inflammatory therapy for the treatment of persistent asthma as recommended by both national and international guidelines. However, an increasing number of studies have demonstrated marked variability in response to ICS with 25% to 35% of subjects with asthma showing little improvement in FEV1 and/or bronchial hyperresponsiveness (BHR). Retrospective analysis of a previous Asthma Clinical Research Network (ACRN) study identified elevated fraction of exhaled nitric oxide (FeNO) and greater bronchodilator reversibility to a short-acting β2-agonist as predictors of a positive FEV1 response to ICS and higher sputum eosinophils and shorter duration of asthma (years since diagnosis) as predictors of improvement in BHR.7 This study did not examine, however, whether these responses in pulmonary function to short-term ICS treatment could predict the long-term response in the maintenance of asthma control with more prolonged treatment. Thus, the ACRN embarked on a larger prospective study to analyze biomarkers and characteristics of asthma as predictors of response to short-term (6-week) ICS treatment and then to examine the relationship of the short-term response to the importance of continued ICS treatment for maintenance of asthma control over a longer time (16 additional weeks).

Participants

Inclusion criteria for study subjects were individuals with asthma between 18 and 55 years of age with a baseline FEV1 55% to 85% predicted and a methacholine PC20 ≤12 mg/mL. No ICS or systemic corticosteroids were allowed for at least 4 weeks before enrollment. No smoking was allowed for 1 year before enrollment, and cumulative exposure was less than 10 pack-years. Additional exclusion criteria regarding patient condition and compliance during the run-in period were applied.

Design

Eighty-three subjects were enrolled into this study. After a 2-week run-in characterization period, the subjects were begun on single-blind ICS, hydrofluoroalkane-beclomethasone proprionate at 160 μg twice daily. This period was used to evaluate biomarkers and characteristics prospectively that would predict ICS response.

After the single-blind period, subjects were stratified on the basis of the FEV1 response to ICS. At this point, the subjects were randomized to a double-blind, placebo-controlled 16-week trial to evaluate asthma control by the primary outcome, the Asthma Control Questionnaire (ACQ). Secondary outcomes were morning peak expiratory flow (PEF) rates, symptom-free days and nights, rescue albuterol use, and exacerbations. We evaluated the PC20 response as a determinant of ICS dependency for maintaining asthma control and other secondary outcomes by a retrospective stratification.

Conclusions

The short-term response to inhaled corticosteroids with regard to FEV1 improvement predicts long-term asthma control.

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