TABLE 5

Associations of chronic cough with lung function after bronchodilator inhalation

VariablesOR or β (95% CI)p-value
FEV1/FVC−3.30 (−4.93– −1.66)0.0005
FEV1 %pred−4.42 (−8.89–0.05)0.0522
FEV1/FVC <70%1.59 (1.13–2.23)0.0106
MMEF % pred−5.73 (−9.06– −2.40)0.0020
FEF 50% pred−7.64 (−12.16– −3.11)0.0023
FEF 75% pred−6.51 (−10.29– −2.74)0.0019
SAD#1.47 (1.14–1.89)0.0049
Positive bronchodilator reversibility1.87 (1.01–3.47)0.0472

Adjusted for age, sex, urbanisation, body mass index, cigarette smoking, biomass, annual mean PM2.5, education, occupational exposure, visible mould spots in the current residence, history of pneumonia or bronchitis during childhood, parental history of respiratory diseases and allergic rhinitis. The logistic or linear regression analyses are weighted, taking into account the multistage cluster sampling design. FEV1: forced expiratory volume in 1 s; FVC: forced vital capacity; MMEF: maximal mid-expiratory flow; FEF 50%: forced expiratory flow at 50% of the FVC; FEF 75%: forced expiratory flow at 50% of the FVC; SAD: small airway dysfunction. #: SAD was diagnosed on the basis of at least two of the following three indicators of lung function being <65% of predicted – MMEF, FEF 50% and FEF 75% after bronchodilator inhalation; : a positive bronchodilator reversibility test was defined as an increase in post-bronchodilator forced expiratory volume in 1 s of >12% and >200 mL from baseline, 20 min after inhalation of 400 µg of salbutamol.