Physical activity associates with disease characteristics of severe asthma, bronchiectasis and COPD

Background and objective: Physical activity (PA) in obstructive airway diseases (OAD) is likely to be impaired but this has not been extensively studied outside of chronic obstructive pulmonary disease (COPD). We describe PA levels in severe asthma and bronchiectasis compared to moderate¿severe COPD and to controls, and tested the cross-sectional associations of PA (steps/day) with shared disease characteristics in the OAD group. Methods: Adults with OAD (severe asthma = 62, COPD = 67, bronchiectasis = 60) and controls (n = 63) underwent a multidimensional assessment, including device-measured PA levels. Results: The OAD group included 189 participants (58.7% females), with median (interquartile range) age of 67 (58¿72) years and mean forced expiratory volume in the first second (FEV 1 ) % predicted of 69.4%. Demographic characteristics differed between groups. Compared to controls (52.4% females, aged 55 (34¿64) years, median 7640 steps/day), those with severe asthma, bronchiectasis and COPD accumulated less steps/day: median difference of -2255, -2289, and -4782, respectively (P = 0.001). Compared to COPD, severe asthma and bronchiectasis participants accumulated more steps/day: median difference of 2375 and 2341, respectively (P = 0.001). No significant differences were found between the severe asthma and bronchiectasis group. Exercise capacity, FEV 1 % predicted, dyspnoea and systemic inflammation differed between groups, but were each significantly associated with steps/day in OAD. In the multivariable model adjusted for all disease characteristics, exercise capacity and FEV 1 % predicted remained significantly associated. Conclusion: PA impairment is common in OAD. The activity level was associated with shared characteristics of these diseases. Interventions to improve PA should be multifactorial and consider the level of impairment and the associated characteristics.