Since reduced physical activity is an independent predictor of outcome in patients with COPD, its measurement is desirable. We evaluated an activity-monitoring device, the Intelligent Device for Energy Expenditure and Activity (IDEEA). This has 5 sensors attached to the skin; these send motion input via 3 wire leads to a device worn at the waist.
Ten COPD patients were studied; each recorded into a log sheet the type and duration of all physical activities in 26 ½-hour epochs over 13 hours. Patient-recorded activity was converted into kilocalories (Kcal), using metabolic equivalent (MET) standard tables and a conversion formula. Patients wore a tri-axial accelerometer (RT3) at the waist and the IDEEA during the study. The RT3, which has been tested in COPD patients, was used for comparison. Both devices have software that estimates energy expenditure from movement. Estimated energy expenditure (EEE) in Kcal from the two devices and direct recording were compared using Pearson's correlations, Bland-Altman plots, and paired t-tests.
Seven females and 3 males were studied; their mean age was 69 ± 7 years and their FEV1 was 46 ± 14 % of predicted. Total EEE (over 13 hours) from direct reporting (1538 ± 456 Kcal) was somewhat higher that from the IDEEA (1441 ± 456 Kcal, p. = 0.05) and considerably higher than from the RT-3 (1105 ± 310 Kcal, p. = < 0.0001). EEE over the 26 ½-hour epochs from direct-reporting correlated only moderately with the IDEEA and RT3 (r = 0.67 and 0.63, respectively, p. < 0.001), and agreement using Bland Altman plots was low. However, the two devices correlated highly with each other: r = 0.88, p. < 0.0001.
In our COPD study patients, the IDEEA gave a closer approximation to directly-reported total EEE than the RT3. However, EEE correlations between the two devices and direct observation were only moderate.
Accurately measuring activity with a non-intrusive motion detector remains a desirable goal.
Patrick Koo, No Financial Disclosure Information; No Product/Research Disclosure Information