Agreement of classification of COPD patients' physical activity with two activity monitors

Rationale It is unclear whether different activity monitors provide similar classification of physical activity (PA) in patients with COPD. Aim To test whether similar PA classification of patients would be obtained when using 2 valid activity monitors. Methods We assessed PA for 4 weeks with Actigraph [(ACT: Steps and vector magnitude units (VMU)] and Dynaport [DAM: Steps, Movement intensity (MI), VMU] activity monitor in 236 COPD patients (FEV1 57±20%pred; 6MWD 430±125m) from 5 European centers resulting in 6776 patient-days. Results ACT and DAM had respectively 11% and 6% missing patient-days and 11% and 12% patient-days had less than 8h of assessment. Steps per day recorded on ACT (mean±SD: 4248±2740) were lower than DAM (4767±2859, p Conclusions The PA values recorded on both monitors differed by a small, but statistically significant amount. Classification of patients in deciles renders very similar results with both ACT and DAM.