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 (EESAB) 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 EESAB, agreement between EESAB and EE measured via indirect calorimetry (EEIC), and its repeatability in COPD. Methods 26 people with COPD (forced expiratory volume in 1 s (FEV1)=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 EESAB and EEIC were collected. The protocol was repeated on a second day. Results EESAB 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 EESAB and EEIC was -0.2 METs (p=0.21) with a limit of agreement of 1.3 METs. The difference between days in EESAB was 0.0 METs with a coefficient of repeatability of 0.4 METs. Rollator use increased the variability in EESAB, compromising its repeatability and agreement with EEIC. Conclusions EESAB was sensitive to small but important changes. There was fair agreement between EESAB and EEIC, and measurements of EESAB were repeatable. These observations suggest that the SAB is useful for the evaluation of EE in patients with COPD who walk without a rollator.