Effects of regular treatment with combination of salmeterol/fluticasone propionate and salmeterol alone in cough variant asthma

Abstract

Objective: Cough variant asthma (CVA) is an important cause of chronic cough, and pathophysiological features of the disease appear to be similar to typical asthma. Because CVA is recognized as a precursor of asthma, early intervention with long-term anti-inflammatory agents may be recommended. However, the role of combination therapy with inhaled corticosteroid and β2-agonist in the treatment of CVA has not been elucidated. To evaluate the effectiveness of the combination therapy, we investigated the clinical impact of regular treatment with salmeterol/fliticasone propionate combination (SFC) and inhaled salmeterol (SAL) alone in patients with CVA. Methods: The study was a randomized, controlled, parallel-group multi-center trial. Forty-three CVA patients were assigned to SFC (50/100 µg once daily) or SAL (50 µg twice daily) for 12 weeks. Then, these medications were stopped for the next 24 weeks. Main outcome measures were cough symptoms, pulmonary function and airway inflammation. Results: Treatment with each of SFC and SAL significantly decreased cough scores and increased FEV1 and PEF, where the efficacy was more pronounced with SFC than SAL. SFC also decreased sputum eosinophil counts and eosinophil cationic protein contents, whereas SAL had no effect. After discontinuation of the treatment, cough scores increased, pulmonary function and eosinophilic airway inflammation were aggravated and returned to the baseline levels. Conclusions: Maintenance therapy with SFC provides further improvements in cough symptoms, pulmonary function and airway inflammation, and discontinuation of the therapy causes worsening of the disease, indicating that stopping or interrupting anti-inflammatory therapy may not be advisable in patients with CVA.