Table 5. Pathophysiology: cough reflex sensitivity in respiratory disease.
| Disease | Observed traits of cough reflex sensitivity |
|---|---|
| Asthma | CRS heightened in asthma compared to health (22,50,51,82,83) |
| CRH associated with worse asthma control, frequent exacerbations (≥2 per annum) and hospitalisation but not FEV1 (84) | |
| CRS associated with cough severity VAS (r=−0.32) and subjective cough frequency (r=−0.38) (22) | |
| CRS associated with objective CFreq and ACQ. CRS not associated with FeNO or serum eosinophils (51) | |
| Methacholine-induced bronchoconstriction increases CRS (85) | |
| CRH more likely in non-atopic compared to atopic asthma (51,84) | |
| COPD | CRS heightened in COPD compared to health (1,19,22,86) |
| CRS is associated with objective CFreq (1,3,71) | |
| Change in CRS between exacerbation and 6-week recovery associated with future exacerbation rate (ρ=−0.69) (87) | |
| CRS not significantly different between current/ex/never smokers (1) | |
| Bronchiectasis | CRS heightened in stable bronchiectasis compared to health (23,88) |
| CRH associated with duration, disease severity (BSI and HRCT), Pseudomonas aeruginosa, female, cough symptom score, worse LCQ (23) | |
| ILD | CRS heightened in IPF and SSc-ILD compared to health (21,89) |
| No association between CRS and cough severity VAS, lung function (FEV1, FVC, DLCO), or radiological disease severity (21,89) | |
| In SSc, CRS higher in those with ILD than without (90) | |
| Sarcoidosis | CRS heightened in sarcoidosis compared to health (4) |
| CRS associated with objective CFreq (r=−0.64) (4) | |
| CRH associated with lower serum ACE level (r=0.72) (4,62) |
CRS, cough reflex sensitivity; CRH, cough reflex hypersensitivity; FEV1, forced expiratory volume in 1 second; VAS, visual analogue scale; CFreq, cough frequency; ACQ, Asthma Control Questionnaire; FeNO, fractional exhaled nitric oxide; COPD, chronic obstructive pulmonary disease; BSI, Bronchiectasis Severity Index; HRCT, high-resolution computed tomography; LCQ, Leicester Cough Questionnaire; IPF, idiopathic pulmonary fibrosis; SSc, systemic sclerosis; ILD, interstitial lung disease; FVC, forced vital capacity; DLCO, diffusing capacity of the lungs for carbon monoxide; ACE, angiotensin converting enzyme.