A Longitudinal Study Evaluating the Effect of Exacerbations on Physical Activity in Patients with COPD

Background Physical inactivity is common in stable COPD and independently predicts poor outcomes. Longitudinal assessments of physical activity in outpatients with COPD, covering periods of stability and exacerbations, have not been evaluated previously.

Methods Patients with clinically-stable COPD and a history of 2 or more clinical exacerbations in the preceding 12 months were recruited. Physical activity was measured using a tri-axial accelerometer (ActiGraph GT3X+) worn continuously on the non-dominant wrist. Mean minutes per day of higher level physical activity was the primary outcome variable. Symptom-defined exacerbations were assessed using the 14-item Exacerbations of Chronic Pulmonary Disease Tool (EXACT) daily dairy. Clinically-reported exacerbations were also captured. Minutes per day of higher level physical activity during exacerbation and non-exacerbation days were compared using a mixed model analysis.

Results Seventeen patients were followed for 135 ± 18 days. Nine were male with a mean age of 63 ±12 years and mean FEV1 of 52 ± 20 %. Fifteen patients had 27 symptom (EXACT) defined exacerbations, including 9 that were also clinically-reported. Patients spent fewer minutes per day at a higher level physical activity during exacerbation days than nonexacerbation days: 131 ± 14 vs.157 ± 14 minutes, p<0.0001. The greatest reduction in physical activity was during the first week of the exacerbation; activity remained low for approximately 2 weeks after exacerbation resolution.

Conclusions Physical activity decreased significantly during exacerbations. Reduction in activity occurs early during an exacerbation and persists for about 2 weeks following symptomatic recovery.