Physical activity and the frequency of acute exacerbations in patients with chronic obstructive pulmonary disease

Introduction Acute exacerbations (AE) of chronic obstructive pulmonary disease (COPD) constitute a substantial burden for COPD patients. Characterized by a worsening of symptoms that is beyond the normal day to [...]
Purpose Acute exacerbations (AE) in patients with COPD are associated with a decline in lung function, increased risk of hospitalization, and mortality. In this cross-sectional study we tested whether the level of objectively measured daily physical activity and exercise capacity are associated with the number of COPD exacerbations. Methods In 210 patients with COPD (67 % men; mean (SD) age: 63 (8) years) enrolled in The Obstructive Pulmonary Disease Outcomes Cohort of Switzerland (TOPDOCS) physical activity (PA) (steps per day, physical activity level, (PAL)), exercise capacity (6-min walking distance, (6MWD)), comorbidities, lung function, and medication were assessed. Differences between COPD patients with frequent (>2 year) and infrequent (0-1 year) exacerbations were assessed. Univariate and multivariate analyses were performed to investigate whether the level of objectively measured daily physical activity and exercise capacity are associated with the number of COPD exacerbations. Results Patients with frequent AE had a significantly lower [FEV.sub.1] and 6MWD compared to patients with infrequent AE. In univariate analysis, the number of exacerbations was inversely associated with [FEV.sub.1], 6MWD, BMI, and smoking status while there was a positive association with RV/TLC and combined inhaled medication. However, there was no significant association with PAL and steps per day. In multivariate analysis, [FEV.sub.1] and the use of combined inhaled medication were independently associated with the number of AE, after correction for covariates. Conclusions The findings of this study imply that [FEV.sub.1], independent of inhaled medication, is significantly associated with COPD exacerbations. Neither physical activity nor exercise capacity was independently associated with COPD exacerbations. Keywords COPD * Acute exacerbations * Objective assessment of daily physical activity * Exercise capacity