Abstract
Wrist-worn accelerometers are often applied to measure arm use after stroke. They measure arm movements during all activities, including whole-body movements, such as walking. Whole-body movements may influence clinimetric properties of arm use measurements—however, this has not yet been examined. This study investigates to what extent arm use measurements with wrist-worn accelerometers are affected by whole-body movements. Assuming that arm movements during whole-body movements are non-functional, we quantify the effect of whole-body movements by comparing two methods: Arm use measured with wrist-worn accelerometers during all whole-body postures and movements (P&M method), and during sitting/standing only (sit/stand method). We have performed a longitudinal observational cohort study with measurements in 33 stroke patients during weeks 3, 12, and 26 poststroke. The P&M method shows higher daily paretic arm use outcomes than the sit/stand method (p < 0.001), the mean difference increased from 31% at week three to 41% at week 26 (p < 0.001). Differences in daily paretic arm use between methods are strongly related to daily walking time (r = 0.83–0.92). Changes in the difference between methods are strongly related to changes in daily walking time (r = 0.89). We show that not correcting arm use measurements for whole-body movements substantially increases arm use outcomes, thereby threatening the validity of arm use outcomes and measured arm use changes.
Highlights
In approximately 80% of the cases, a stroke leads to impairments in arm function in terms of muscle strength, voluntary control, coordination, and range of motion [1]
Arm use data were missing in three participants as a result of a technical failure of the sensor system or non-wear of the system
This study shows that whole-body movements increase cross-sectionally measured arm use outcomes of wrist-worn accelerometers with 8–41% if not correcting arm use data for whole-body movements
Summary
In approximately 80% of the cases, a stroke leads to impairments in arm function in terms of muscle strength, voluntary control, coordination, and range of motion [1]. Wrist-worn accelerometers are often applied to measure arm use after stroke. Wrist-worn accelerometers have been used to assess arm use during rehabilitation poststroke [3,4,5], and to compare arm use levels between stroke patients and healthy subjects [6,7]. Wrist-worn accelerometers have been applied to compare the arm use levels between the paretic and nonparetic arm after stroke [6,8]. Studies explored the relationship between paretic arm use measured with wrist-worn accelerometers, arm function, and arm capacity after stroke [3,9]. The change in arm use after stroke measured with wrist-worn accelerometers and the potential moderating role of psychological factors have been investigated [4]
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