Validity and Accuracy of Step Count as an Indicator of a Sedentary Lifestyle in People With Chronic Obstructive Pulmonary Disease

• Published in: Archives of physical medicine and rehabilitation Vol. 104; no. 8; pp. 1243 - 1252
• Main Authors: Cheng, Sonia W.M., Alison, Jennifer A., Stamatakis, Emmanuel, Dennis, Sarah M., McKeough, Zoe J.
• Format: Journal Article
• Language: English
• Published: United States Elsevier Inc 01.08.2023
• Subjects: Accelerometry; Chronic obstructive pulmonary disease; Physical activity; Rehabilitation; Sedentary behavior; Sedentary behavior; Physical activity; CI; AUC; SB; PA; Chronic obstructive pulmonary disease; FEV1; Rehabilitation; 6MWD; Accelerometry; MVPA; COPD
• ISSN: 0003-9993; 1532-821X
• DOI: 10.1016/j.apmr.2023.01.020

To determine the validity and accuracy of <5000 steps/day as a sedentary lifestyle indicator, and the optimal step count cut point value for indicating a sedentary lifestyle in people with chronic obstructive pulmonary disease (COPD). Analysis of baseline data from a randomized clinical trial. Sydney, Australia. Stable COPD on the waitlist for pulmonary rehabilitation. Not applicable. Step count and time in sedentary behavior (SB) were assessed using thigh-worn accelerometry. A sedentary lifestyle was defined as <5000 steps/day. Pearson correlation coefficients were analyzed between step count and time spent in SB. Sensitivity, specificity, and accuracy were calculated for the <5000 steps/day threshold. Receiver operating characteristic curves with the area under the curve were computed for step count in identifying a sedentary lifestyle. 69 people with COPD (mean age=74 years, SD=9; forced expiratory volume in 1 second, mean=55%, SD=19 predicted) had sufficient wear data for analysis. There was a moderate inverse correlation between step count and time spent in SB (r=−0.58, P<.001). Step count had a fair discriminative ability for identifying a sedentary lifestyle (area under the curve=0.80, 95% confidence interval [CI], 0.68-0.91). The <5000 steps/day threshold had a sensitivity, specificity, and accuracy of 82% (95% CI, 70-94), 70% (95% CI, 54-86), and 78%, respectively. A lower threshold of <4300 steps/day was more accurate for ruling in a sedentary lifestyle. Compared with thigh-worn accelerometry, <5000 steps/day is a valid and reasonably accurate indicator of a sedentary lifestyle in this population.