Activity monitoring for assessment of physical activities in daily life in patients with chronic obstructive pulmonary disease

Objective: To investigate the degree of agreement between different methods of assessing physical activities in daily life in patients with chronic obstructive pulmonary disease (COPD): video recordings (criterion standard), the DynaPort Activity Monitor (DAM), and patient self-report. Design: Study A: outcomes from video recordings were compared with DAM outcomes and with patient estimation of time spent on each activity after a 1-hour protocol including walking, cycling, standing, sitting, and lying. Study B: DAM outcomes and patient self-report were compared during I day in real life. Setting: Outpatient clinic in a university hospital. Participants: Study A: 10 patients with COPD (mean age, 62 +/- 6y; forced expiratory volume in the first second [FEV1]=40% +/- 16% of predicted). Study B: 13 patients with COPD (mean age, 61 +/- 8y; FEV1 =33% +/- 10% of predicted). Interventions: Not applicable. Main Outcome Measures: Time spent on different activities and movement intensity during walking and cycling. Results: Study A: time estimated by the patients in the sitting position was significantly lower than the time showed by the video recordings and the DAM (both P <.001). For the other variables, there were no statistically significant differences (all P >.05). However, Bland and Altman plots and intraclass correlation coefficients showed large disagreement between video recordings and patients' estimations, in contrast to the high degree of agreement between video recordings and DAM. Changes in walking speed correlated highly to changes in DAM movement intensity (r=.81, P <.01). Study B: patients significantly overestimated walking time (22 +/- 47min, P=.04) and underestimated standing time (-45 +/- 71min, P=.04). Conclusions: The DAM showed high accuracy in objectively assessing time spent on different activities and changesin walking speed in patients with COPD. Patients' estimations of time spent on physical activities in daily life disagreed with objective assessment.