Measurement properties of the SenseWear armband in adults with chronic obstructive pulmonary disease

RATIONALE: The SenseWear armband (SAB) is designed to measure energy expenditure (EE). In people with chronic obstructive pulmonary disease (COPD), EE estimated using the SAB (EE(SAB)) is a popular outcome measure. However, a detailed analysis of the measurement properties of the SAB in COPD is lacking. OBJECTIVE: To examine the sensitivity of EE(SAB), agreement between EE(SAB) and EE measured via indirect calorimetry (EE(IC)), and its repeatability in COPD. METHODS: 26 people with COPD (forced expiratory volume in 1 s (FEV(1))=49+/-18% predicted; 15 males) spent 6 min in five standardised tasks that comprised supine, sitting, standing and two walking speeds. A subgroup (n=12) walked using a rollator. Throughout each task, measurements of EE(SAB) and EE(IC) were collected. The protocol was repeated on a second day. RESULTS: EE(SAB) increased between standing and slow walking (2.4, metabolic equivalents (METs) 95% CI 2.2 to 2.7) as well as slow and fast walking (0.5 METs, 95% CI 0.3 to 0.7). Considering all tasks together, the difference between EE(SAB) and EE(IC) was -0.2 METs (p=0.21) with a limit of agreement of 1.3 METs. The difference between days in EE(SAB) was 0.0 METs with a coefficient of repeatability of 0.4 METs. Rollator use increased the variability in EE(SAB), compromising its repeatability and agreement with EE(IC). CONCLUSIONS: EE(SAB) was sensitive to small but important changes. There was fair agreement between EE(SAB) and EE(IC), and measurements of EE(SAB) were repeatable. These observations suggest that the SAB is useful for the evaluation of EE in patients with COPD who walk without a rollator.