• Heleen Demeyer, Chris Burtin, Hans Van Remoortel, Miek Hornikx, Daniel Langer, Marc Decramer, Rik Gosselink, Wim Janssens, and Thierry Troosters.
• Faculty of Kinesiology and Rehabilitation Sciences, Department of Rehabilitation Sciences, KU Leuven, Leuven, Belgium; Respiratory Rehabilitation and Respiratory Division, University Hospital Leuven, Leuven, Belgium.
• Chest. 2014 Aug 1; 146 (2): 318327318-327.

BackgroundThere is a wide variability in measurement methodology of physical activity. This study investigated the effect of different analysis techniques on the statistical power of physical activity outcomes after pulmonary rehabilitation.MethodsPhysical activity was measured with an activity monitor armband in 57 patients with COPD (mean ± SD age, 66 ± 7 years; FEV1, 46 ± 17% predicted) before and after 3 months of pulmonary rehabilitation. The choice of the outcome (daily number of steps [STEPS], time spent in at least moderate physical activity [TMA], mean metabolic equivalents of task level [METS], and activity time [ACT]), impact of weekends, number of days of assessment, postprocessing techniques, and influence of duration of daylight time (DT) on the sample size to achieve a power of 0.8 were investigated.ResultsThe STEPS and ACT (1.6-2.3 metabolic equivalents of task) were the most sensitive outcomes. Excluding weekends decreased the sample size for STEPS (83 vs 56), TMA (160 vs 148), and METS (251 vs 207). Using 4 weekdays (STEPS and TMA) or 5 weekdays (METS) rendered the lowest sample size. Excluding days with < 8 h wearing time reduced the sample size for STEPS (56 vs 51). Differences in DT were an important confounder.ConclusionsChanges in physical activity following pulmonary rehabilitation are best measured for 4 weekdays, including only days with at least 8 h of wearing time (during waking hours) and considering the difference in DT as a covariate in the analysis.Trial RegistryClinicalTrials.gov; No.: NCT00948623; URL: www.clinicaltrials.gov.

20 keywords...

hide…