Objective Physical Activity Measurement in COPD

Physical activity was measured by average daily step counts assessed objectively using pedometers: Omron HJ-720 ITC pedometer (cohort 1 and 2) and Fitbit Zip (cohort 3). We have previously demonstrated that pedometers can accurately capture daily step counts among Veterans with COPD [31 (link), 32 (link)].
Criteria for valid wear days are detailed in Table 1. All participants in both groups were blinded to step-count feedback during a 7-day baseline collection period prior to randomization using an opaque sticker covering the pedometer face (preventing feedback of daily step counts). After the baseline collection period, study participants were not blinded to step-count data. Group 1 participants had access to pedometers throughout the study. Monitoring of group 2 participants varied by study. Participants from cohort 2 had access to an Omron pedometer throughout the study and were not blinded to step counts after initial baseline data collection. Participants from cohort 3 had access to the study pedometer only during the baseline collection period and for 14-days after the 3-month study visit. The MCID for daily step counts in persons with COPD ranges from 350 to 1100 steps/day [33 (link), 34 (link)].