Published in:
Open Access 01-12-2005 | Research
Change in bronchial responsiveness and cough reflex sensitivity in patients with cough variant asthma: effect of inhaled corticosteroids
Published in: Cough | Issue 1/2005
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Background
Cough variant asthma (CVA) is a cause of chronic cough and a precursor of typical asthma. We retrospectively examined the longitudinal change in bronchial responsiveness and cough reflex sensitivity in CVA patients with respect to the effect of long-term inhaled corticosteroids (ICS).
Methods
Provocative concentration of methacholine causing a 20% fall in forced expiratory volume in one second (PC20-FEV1) and provocative concentration of capsaicin eliciting 5 or more coughs (C5) were measured before treatment and during a follow up period following relief of cough (median; 2.0 (range; 0.5 to 8.0) years after the initial visit) in a total of 20 patients with CVA (7 males and 13 females, mean ± SD age of 49.9 ± 12.9 years).
Results
Three of 8 patients not taking long-term ICS developed typical asthma compared to none of 12 patients taking ICS (p = 0.0171). PC20-FEV1 significantly (p < 0.0001) increased from 1.80 (GSEM, 1.35) to 10.7 (GSEM, 1.63) mg/ml in patients taking ICS but did not change in patients not taking ICS [2.10 (GSEM, 1.47) compared to 2.13 (GSEM, 1.52) mg/ml]. Cough threshold did not change in patients whether taking or not taking ICS.
Conclusion
Long-term ICS reduces bronchial hyperresponsiveness in CVA as recognized in typical asthma. Cough reflex sensitivity is not involved in the mechanism of cough in CVA.