Bronchodilator Responsiveness and Reported Respiratory Symptoms in an Adult Population

Background The relationship between patient-reported symptoms and objective measures of lung function is poorly understood. Aim To determine the association between responsiveness to bronchodilator and respiratory symptoms in random population samples. Methods 4669 people aged 40 years and older from 8 sites in Canada completed interviewer-administered respiratory questionnaires and performed spirometry before and after administration of 200 ug of inhaled salbutamol. The effect of anthropometric variables, smoking exposure and doctor-diagnosed asthma (DDA) on bronchodilator responsiveness in forced expiratory volume in 1 second (FEV 1 ) and in forced vital capacity (FVC) were evaluated. Multiple logistic regression was used to test for association between quintiles of increasing changes in FEV 1 and in FVC after bronchodilator and several respiratory symptoms. Results Determinants of bronchodilator change in FEV 1 and FVC included age, DDA, smoking, respiratory drug use and female gender [p<0.005 to p<0.0001 ]. In subjects without doctor-diagnosed asthma or COPD, bronchodilator response in FEV 1 was associated with wheezing [p for trend<0.0001], while bronchodilator response for FVC was associated with breathlessness. [p for trend <0.0001]. Conclusions Bronchodilator responsiveness in FEV 1 or FVC are associated with different respiratory symptoms in the community. Both flow and volume bronchodilator responses are useful parameters which together can be predictive of both wheezing and breathlessness in the general population.