Abstract
Activity monitors are increasingly used to assess physical activity. We aimed to compare wearing time and walking between two activity monitors in COPD. Fifty four patients (FEV1 62±22%pred, 6MWD 495±138m) wore the Actigraph (AG) and Dynaport (DP) twice for 14 days with 14 days in between, in the frame of the PROactive project. Wearing time (h/d); walking time(min/d) of DP (DPWT) and steps/day of AG (AGsteps) were retrieved. Calculations were done on the mean wearing and walking variables obtained over 28 days (Inter-patient correlations). Intra-patient correlations were calculated over the 28 days obtained in each patient, as well as between mean weekly values of the 4 weeks (6 contrasts). Results: wearing time of the AG and DP were strongly related (R=0.80 p<0.001). Despite being worn on the same belt the DP reported 83±69min more wearing time (p<0.001). Mean DPWT and AGsteps related strongly (R=0.90 p<0.001). Median day-by-day correlations between AGsteps and DPWT was 0.88 (IQR 0.75 to 0.95). Week-to-week variability was large (AGsteps 424 range -8412 to 8083; DPWT 6 range -79 to 120min). Median correlations of differences in 6 weekly PA levels, (n=39) was good (median R=0.88 IQR 0.71 to 0.98).
These data show that both monitors provide comparable outcomes and are capable of measuring differences between separate weeks of assessment. The difference in wearing time needs clarification.
- © 2012 ERS