Are depressive symptoms related to physical inactivity in chronic obstructive pulmonary disease?

Patients with chronic obstructive pulmonary disease (COPD) are physically inactive, and this predicts poor outcome. Factors influencing activity levels in COPD patients are poorly understood. Depression is common in COPD patients and may influence activity. Accordingly, in this pilot study, we evaluated the relationship between depressive symptoms and activity in clinically stable COPD (forced expiratory volume in 1 second [FEV(1)]/forced vital capacity < 0.70, FEV(1) < 80%). An additional inclusion criterion was the Hospital Anxiety and Depression Scale depression score, which had to be ≤7 or ≥10, representing low and high levels of depressive symptoms, respectively.

Sixteen patients with high depression scores (DEPR) and 20 with low depression scores (non-DEPR), were studied. Physical activity was measured over 7 consecutive days, using the SenseWear armband (BodyMedia Inc, Pittsburgh, PA) worn on the arm.

The mean age was 69 ± 9 years and the FEV(1) was 49 ± 16%. The Hospital Anxiety and Depression Scale depression scores in DEPR and non-DEPR patients were 12.0 ± 2.3 and 3.7 ± 2.0, respectively. There were no significant between-group differences in age, gender, body mass index, FEV(1), supplemental oxygen requirement, and walk distance. DEPR and non-DEPR patients did not differ in estimated steps per day (3490 ± 2020 vs 3634 ± 2000; P = .83) or minutes per day, with activity >3 metabolic equivalents (11 ± 7 vs 13 ± 9; P = .42). Steps correlated with the FEV(1) (r = 0.49; P = .002) and the 6-minute walk distance (r = 0.69; P = .0001).

We were unable to demonstrate a relationship between depressive symptoms and directly measured physical activity level in patients with COPD.