Abstract
Background: The DynaPort Activity Monitor (DAM) has been reported to be useful to evaluate the activity in patients with COPD. However, its battery works for only several hrs and it should be worn at two parts of body. A newly developed compact, single-position triaxial accelerometer (Actimarker) can measure the activity for more than 1 month, but has not been validated for patients with COPD.
Objectives: The validation of the Actimarker in patients with COPD was evaluated and the conditions of day for analysis were determined.
Methods: In study 1, the reproducibility of the Actimarker was evaluated for 14 stable COPD patients by comparing it with DAM. In study 2, the influence of holiday and the weather on the activity was examined. In study 3, the number of measurement days to ensure repeatability was determined.
Results: The differences in the activity by Actimarker and the locomotion by DAM were all within the limit of agreement at the intensity of ≥2.0 METs, ≥2.5 METs and ≥3.0 METs with Bland-Altman Plots. The durations of activity on holidays in patients with jobs and on rainy days were significantly shorter than those on weekdays and on non-rainy days, respectively. The values of intra-class correlation coefficient were more than 0.8 in 3, 4 or 5 day-measurements, and the mean values of duration of activity from 3 or 4 days were all within the limit of agreement with Bland-Altman Plots.
Conclusions: The physical activity assessed by Actimarker was confirmed for its reproducibility and repeatability when the data from 3 non-rainy weekdays were analyzed. Actimarker seems to be useful as a simplified method to evaluate the physical activity in patients with COPD.
- © 2011 ERS
