Cough reflex sensitivity: association with exacerbation frequency in chronic obstructive pulmonary disease

Introduction: Increased cough is common in chronic obstructive pulmonary disease exacerbations (ECOPDs). We hypothesised that cough reflex sensitivity (CRS) is increased during ECOPD, and that CRS is associated with future ECOPD risk. Methods: Patients hospitalised with ECOPD underwent inhaled capsaicin challenges to determine threshold concentrations required to elicit 5 coughs (C5) during admission (TE) and after a 6-week recovery period (TR). Spirometry, cough severity visual analogue scale (VAS) rating, and the COPD Assessment Test (CAT) were completed. In the following 12 months, the number of moderate and severe ECOPDs were recorded (requiring medication change and/or hospital admission, separated by ≥14 days) (Seemungal et al 2000). Results: 16 patients were recruited: mean (SD) age 67 (6.6) years, 9 (56%) female, FEV1 34.6 (10.1) % predicted. C5 was significantly lower at TE than at TR; geometric mean (SD) 1.64 (3.84) vs. 8.94 (6.50) μmol⋅L-1; mean (95% CI) doubling dose difference in C5: 2.46 (0.93-3.57), p Discussion: Cough reflex sensitivity was heightened during ECOPD, and the change in C5 at 6 weeks was associated with exacerbation frequency in the following 12 months. These novel observations require further study.