Effects of Medication Use on Small Airway Function and Airway Inflammation in Patients with Clinically Controlled Asthma

Abstract

To observe effects of medication use on small airway function, airway inflammation and acute exacerbations in patients with clinically controlled asthma. Forced expiratory flow over the middle half of the forced expiratory curve (FEF25%–75%), percentage of eosinophil, concentrations of eosinophil cationic protein (ECP) and interleukin (IL)-5 in induced sputum were assessed in patients with clinically controlled asthma who were given oral anti-inflammatory agents alone or in combination with inhaled therapy and inhaled therapy alone. Subsequently, acute exacerbations were compared between two groups during the 24-week follow-up period. FEF25%–75% in 43 patients with clinically controlled asthma given oral anti-inflammatory agents alone or in combination with inhaled therapy was significantly higher than that in 49 patients given inhaled therapy alone. Meanwhile, the percentage of eosinophils and levels of IL-5 and ECP in patients with clinically controlled asthma given oral anti-inflammatory agents alone or in combination with inhaled therapy were significantly lower than those in patients given inhaled therapy alone. Additionally, the patients with clinically controlled asthma given inhaled therapy were likely to have more acute exacerbation than the patients given oral anti-inflammatory agents alone or in combination with inhaled therapy during the 24-week follow-up period. Systemic anti-inflammatory agents may have a greater effect on parameters reflecting small airway patency and reducing acute exacerbations, presumably secondary to reduction in airway inflammation.