An Open-Label, Multi-Institutional, Randomized Study to Evaluate the Additive Effect of a Leukotriene Receptor Antagonist on Cough Score in Patients with Cough-Variant Asthma Being Treated with Inhaled Corticosteroids.

Cough-variant asthma is one of the most common reasons for chronic cough. It is important to treat appropriately cough-variant asthma because 30% to 40% of cough-variant asthma becomes a typical asthma. However, little is known about the treatment of cough-variant asthma except for inhaled corticosteroid (ICS). The aim of this study was to validate the additive efficacy of a leukotriene receptor antagonist (LTRA) on cough score and respiratory function in patients with cough-variant asthma being treated with ICS. A total 28 patients were randomly assigned to either an ICS + LTRA group or an ICS group. There were statistically significant improvements in cough scores in the ICS + LTRA group from 0 weeks (6.7 ± 4.4) to 2 weeks (2.9 ± 3.2) (P < 0.05), 4 weeks (0.7 ± 1.1) (P < 0.001), and 8 weeks (0.8 ± 1.2) (P < 0.001). However similar improvements were not evident in the ICS group from 0 weeks (6.7 ± 4.4) to 2 weeks (5.6 ± 10.0) (P = 0.59), 4 weeks (4.6 ± 7.6) (P = 0.32), and 8 weeks (2.9 ± 5.2) (P = 0.08). On the other hand, no significant changes were evident in the forced expiratory volume in 1 s (FEV1) and FEV1/forced vital capacity (FVC). In conclusion, the LTRA was useful in improving cough in patients with cough-variant asthma, even though it appeared to be ineffective in improving respiratory function.