Article

OBJECTIVE: To measure the step-count accuracy of an ankle-worn accelerometer, a
thigh-worn accelerometer, and a pedometer in older and frail inpatients. DESIGN:
Cross-sectional design study. SETTING: Research room within a hospital.
PARTICIPANTS: Convenience sample of inpatients (N=32; age, >/=65 years) who were
able to walk 20m independently with or without a walking aid. INTERVENTIONS:
Patients completed a 40-minute program of predetermined tasks while wearing the 3
motion sensors simultaneously. Video recording of the procedure provided the
criterion measurement of step count. MAIN OUTCOME MEASURES: Mean percentage
errors were calculated for all tasks, for slow versus fast walkers, for
independent walkers versus walking-aid users, and over shorter versus longer
distances. The intraclass correlation was calculated, and accuracy was
graphically displayed by Bland-Altman plots. RESULTS: Thirty-two patients (mean
age, 78.1+/-7.8y) completed the study. Fifteen (47%) were women, and 17 (51%)
used walking aids. Their median speed was .46m/s (interquartile range [IQR],
.36-.66m/s). The ankle-worn accelerometer overestimated steps (median error, 1%
[IQR, -3% to 13%]). The other motion sensors underestimated steps (median error,
40% [IQR, -51% to -35%] and 38% [IQR -93% to -27%], respectively). The ankle-worn
accelerometer proved to be more accurate over longer distances (median error, 3%
[IQR, 0%-9%]) than over shorter distances (median error, 10% [IQR, -23% to 9%]).
CONCLUSIONS: The ankle-worn accelerometer gave the most accurate step-count
measurement and was most accurate over longer distances. Neither of the other
motion sensors had acceptable margins of error.
CI - Copyright (c) 2016 American Congress of Rehabilitation Medicine. Published by
Elsevier Inc. All rights reserved.

Langue : ANGLAIS