Cough-reflex sensitivity to inhaled capsaicin in COPD associated with increased exacerbation frequency |
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Authors: | Kunihiko TERADA Shigeo MURO Tadashi OHARA Akane HARUNA Satoshi MARUMO Megumi KUDO Emiko OGAWA Yuma HOSHINO Toyohiro HIRAI Akio NIIMI AND Michiaki MISHIMA |
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Affiliation: | Department of Respiratory Medicine, Kyoto University, Japan |
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Abstract: | Background and objective: The causes of exacerbations in COPD patients are poorly understood. This study examined the association between cough-reflex sensitivity in patients with stable COPD and the frequency of subsequent exacerbations. Methods: The sampling frame for cases and controls for this study was patients attending a hospital outpatient clinic. cough-reflex sensitivity was evaluated using the log concentration of capsaicin causing five or more coughs (log C5). Subsequent COPD exacerbations were identified prospectively via symptom-based diaries over a 12-month period. Results: The study group comprised 45 COPD subjects and 10 controls. Mean log C5 was lower in the COPD group than in the control group (0.97 (95% confidence interval (CI): 0.76–1.18) versus 1.26 (95% CI: 0.81–1.71), P = 0.095). In the COPD group, log C5 was negatively correlated with serum CRP level ( r = −0.36, P = 0.02) and significantly associated with the exacerbation frequency ( r = −0.38, P = 0.01). Stepwise multiple regression analysis showed that cough-reflex sensitivity was significantly associated with exacerbation frequency ( r 2 = 0.15, P = 0.01). Conclusions: Hypersensitivity of the cough reflex to inhaled capsaicin might reflect airway inflammation in stable COPD patients, which predisposes to frequent exacerbations. |
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Keywords: | chronic obstructive pulmonary disease cough-reflex sensitivity C-reactive protein exacerbation inflammation |
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