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Original Research: COPD |

Daily Step Count Is Associated With Plasma C-Reactive Protein and IL-6 in a US Cohort With COPDDaily Step Count and Inflammatory Biomarkers in COPD

Marilyn L. Moy, MD; Merilee Teylan, MPH; Nicole A. Weston, BS; David R. Gagnon, MD, PhD; Valery A. Danilack, MPH; Eric Garshick, MD
Author and Funding Information

From the Department of Veteran Affairs (Drs Moy and Garshick), Veterans Health Administration, Rehabilitation Research and Development Service, Boston, MA; Pulmonary and Critical Care Medicine Section (Drs Moy and Garshick and Mss Teylan, Weston, and Danilack), VA Boston Healthcare System, Boston, MA; Division of Pulmonary and Critical Care Medicine (Dr Moy) and Channing Division of Network Medicine (Dr Garshick), Department of Medicine, Brigham and Women’s Hospital, Boston, MA; Harvard Medical School (Drs Moy and Garshick), Boston, MA; Department of Biostatistics (Dr Gagnon), Boston University School of Public Health, Boston, MA; VA Cooperative Studies (Dr Gagnon), Boston, MA; and Department of Epidemiology (Ms Danilack), Brown University, Providence, RI.

Correspondence to: Marilyn L. Moy, MD, VA Boston Healthcare System, Pulmonary and Critical Care Section, 1400 VFW Parkway, Mail Code 111PI, West Roxbury, MA 02132; e-mail: marilyn.moy@va.gov


Funding/Support: This research was supported by the Department of Veteran Affairs, Veterans Health Administration, Rehabilitation Research and Development Service through a VA Career Development Award to Dr Moy. It also was supported in part by the Center for Integration of Medicine and Innovative Technology, Boston, MA (Dr Moy), and in part by the VA Rehabilitation Research and Development Service [Grant B6618R to Dr Garshick].

Reproduction of this article is prohibited without written permission from the American College of Chest Physicians. See online for more details.


Chest. 2014;145(3):542-550. doi:10.1378/chest.13-1052
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Background:  Physical activity is an important clinical marker of disease status in COPD. COPD is also characterized by low-grade systemic inflammation. However, the relationship between physical activity and systemic inflammation in COPD is unclear.

Methods:  We monitored daily step count, a directly measured physical activity, using the StepWatch Activity Monitor, an ankle-worn accelerometer, in 171 people with stable COPD. Exercise capacity was assessed with the 6-min walk test (6MWT). We measured plasma C-reactive protein (CRP) and IL-6 levels. Linear regression models examined the cross-sectional associations of daily step count and 6MWT distance with CRP and IL-6 levels.

Results:  Subjects had a mean age 72 ± 8 years and mean FEV1 1.5 ± 0.57 L (54 ± 20% predicted). Median daily step count was 5,203 (interquartile range [IQR], 3,627-7,024], CRP level was 2.4 mg/L (IQR, 1.2-5.0), and IL-6 level was 2.9 pg/mL (IQR, 2.0-5.1). Each 1,000-step increase in daily step count was associated with a 0.94 mg/L and 0.96 pg/mL decrease in CRP (P = .020) and IL-6 (P = .044) levels, respectively, adjusting for age, FEV1 % predicted, pack-years smoked, cardiac disease, current statin use, history of acute exacerbations, and season. There was a significant linear trend of increasing daily step count by quartiles and decreasing CRP (P = .0007) and IL-6 (P = .023) levels. Higher 6MWT distance was also significantly associated with lower CRP and IL-6 values.

Conclusion:  People with COPD who walked the most had the lowest plasma CRP and IL-6 levels. These results provide the conceptual basis to study whether an intervention to promote walking will reduce systemic inflammation in people with COPD.


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