Cough reflex sensitivity in patients with cough variant asthma

Abstract

Background: the sensitivity of cough reflex is an important factor influencing cough severity and response to treatment, irrespective of the underlying cause of chronic cough (CC). Objective: to analyze factors influencing cough reflex sensitivity measured by capsaicin inhalation cough challenge in patients with cough variant asthma (CVA). Methods: the study included 34 patients with CVA. Cough reflex sensitivity was measured by capsaicin inhalation cough challenge in all patients. Clinical characteristics, duration of cough, Leicester Cough Questionnaire (LCQ) and VAS score, severity of bronchial hyperresponsiveness (PC20), FeNO, induced sputum (IS) cellular composition and blood eosinophil count were analyzed in relation to cough reflex sensitivity (measured as C2 and C5). Results: we found a negative correlation between C2 or C5 and Reflux Index Score (RSI) (r=-0.51, p=0.015 and r=-0.48, p=0.023, respectively). Cough reflex sensitivity correlated neither with bronchial hyperresponsiveness (PC20) nor with blood or IS eosinophilia. When patients with higher (C5≤7.84 µM) and lower (C5>7.84 µM) cough reflex sensitivity were compared, a longer cough duration (102 vs 48 months, p=0.035) and a higher incidence of GER symptoms (62% vs 19%, p=0.031; RSI 17 vs 14 points, p=0.021) were found in the first group. There were no differences between these groups in demographic data, cough severity, cough reasons and efficacy of anti-asthmatic therapy. Conclusions: in patients with CVA, high cough reflex sensitivity was related to coincidence of GER and duration of CC, but not to bronchial hyperresponsiveness.