Background: Evidence from longitudinal studies on the impact of exacerbation symptoms on physical activity in chronic obstructive pulmonary disease (COPD) is lacking. The aim of this first exploratory study was to assess the association between exacerbation symptoms and physical activity, and to quantify the relative influence of specific symptoms.
Methods: We recruited COPD patients at high risk for exacerbations from 2 pulmonary rehabilitation clinics and 1 acute care clinic in Switzerland. For 3 months after discharge, patients completed a daily symptom diary on a smartphone application, the EXAcerbations of Chronic pulmonary disease Tool (EXACT), and wore a pedometer to measure daily steps. We used mixed-effects models to determine the association of daily steps with exacerbation symptoms.
Results: A total of 21 patients (Global Initiative for Chronic Obstructive Lung Disease grades 2-4) were enrolled for a mean of 94.4 days (standard deviation 4.2). The baseline median number of daily steps was 3,264.6 (interquartile range [IQR]: 1,851.3-4,784.1) and EXACT score was 37.0 (IQR: 30.9-41.4). A 12-point increase in EXACT score (indicating the start of an exacerbation) was statistically significantly associated with a decrease in daily steps of 653.3 (95% CI 969.7-336.9). Chest symptoms (tightness, discomfort and congestion) were more strongly associated with change in steps than breathlessness, and cough and sputum (z-value -4.5 vs -2.9 and -3.0).
Conclusion: This is the first study to show that, in a small cohort of COPD patients, increases in exacerbation symptoms were associated with a statistically and clinically significant reduction in daily physical activity. These results underscore the importance for symptom control and exacerbation prevention in COPD patients.
Keywords: COPD; PRO; exacerbation; longitudinal; management; physical activity; step count; symptoms.