Daily physical activity and related risk factors in COPD

BACKGROUND: Factors associated with reduced daily physical activity (DPA) in patients with COPD are still controversial. Physical inactivity in COPD increases risk of cardiovascular disease, frequent exacerbations, reduced health status, and increased symptoms. We hypothesised that reduced DPA in patients with COPD is independent of traditional risk factors including age and spirometry. METHODS: In this cross-sectional study, DPA (over 7 days) was assessed on 88 community stable patients with COPD and 40 controls free from cardiorespiratory disease. Spirometry, body composition, number of exacerbations, handgrip strength (HGS), modified Medical Research Council (mMRC), arterial stiffness, 6-min walking distance (6MWD) and BODE index were also determined. Frequent exacerbation was defined as ≥2 and non-frequent exacerbation < 2. RESULTS: Patients with COPD had reduced DPA and exercise capacity compared with controls similar in age, BMI and gender, p < 0.001. Frequent exacerbators had less DPA than infrequent exacerbators and both less than controls, p < 0.001. Patients with higher BODE index were less active than those with lower index. Time spent on moderate activity was related to cardiovascular risk factors including arterial stiffness. The DPA in patients was independent of age, gender, spirometry, body composition and HGS, p > 0.05. The level of breathlessness was superior to lung function in predicting the level of DPA. CONCLUSION: The level of DPA in COPD was independent of traditional risk factors. Breathlessness score is a better predictor of the DPA than lung function and handgrip strength.