Role of symptoms and lung function in determining asthma control in smokers with asthma

Cigarette smoking in asthma increases the severity and accelerates the decline in lung function. The relative role of symptoms and lung function in determining asthma control in smokers with asthma is not known. The aim of this study was to compare asthma control in smokers vs never-smokers with asthma, using the validated Juniper asthma control questionnaire (ACQ), and assess if any difference was because of a particular symptom or the forced expiratory volume in one second (FEV1) value. This was a cross-sectional study of 134 asthmatics (74 never-smokers and 60 smokers) with >= 15% reversibility in FEV1 after salbutamol. All subjects completed the ACQ, recording FEV1 and asthma symptoms (night awakening, morning symptoms, dyspnoea, wheeze, activity limitation and use of reliever inhaler). Compared with the never-smokers, smokers with asthma had significantly worse median (IQR) total asthma control score [1.6 (1.1-2.3) vs 2.8 (1.7-3.4); (P < 0.0001)] and in each of the six individual symptom question scores (P < 0.001), but no difference in FEV1 levels (P = 0.908). Asthma control is significantly worse in asthmatics who smoke compared with never-smokers, with all symptoms related to asthma control uniformly worse in smokers, independent of FEV1.