Cough-reflex sensitivity to inhaled capsaicin in COPD associated with increased exacerbation frequency

Respirology. 2009 Nov;14(8):1151-5. doi: 10.1111/j.1440-1843.2009.01620.x. Epub 2009 Sep 16.


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 C(5)). 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 C(5) 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 C(5) 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.

Publication types

  • Controlled Clinical Trial

MeSH terms

  • Aged
  • C-Reactive Protein / metabolism
  • Capsaicin / adverse effects*
  • Causality
  • Cough / epidemiology
  • Cough / physiopathology*
  • Forced Expiratory Volume / physiology
  • Humans
  • Male
  • Outcome Assessment, Health Care
  • Prevalence
  • Pulmonary Disease, Chronic Obstructive / physiopathology*
  • Reflex / physiology*
  • Regression Analysis
  • Respiratory Hypersensitivity / blood
  • Respiratory Hypersensitivity / chemically induced*
  • Respiratory Hypersensitivity / physiopathology*
  • Sensory System Agents / adverse effects
  • Severity of Illness Index*
  • Vital Capacity / physiology


  • Sensory System Agents
  • C-Reactive Protein
  • Capsaicin