Accepted for/Published in: JMIR Rehabilitation and Assistive Technologies
Date Submitted: Mar 20, 2019
Date Accepted: Jun 27, 2019
Accuracy and precision of three consumer-grade activity monitors during over-ground and treadmill walking in Parkinson’s disease.
ABSTRACT
Background:
Wearable motion sensors are gaining popularity for monitoring free-living physical activity among people with Parkinson’s disease (PD), but more evidence supporting the accuracy and precision of motion sensors for capturing step counts is required in PD.
Objective:
This study examined the accuracy and precision of three common consumer-grade motion sensors for measuring actual steps taken during prolonged periods of over-ground and treadmill walking in people with Parkinson’s disease (PD).
Methods:
Thirty-one ambulatory participants with PD underwent 6-minute bouts of over-ground and treadmill walking at a comfortable speed. Participants wore three devices (Garmin Vivosmart 3, Fitbit ONE, and Fitbit Charge 2 HR) and actual steps taken were manually counted by a single researcher. Accuracy and precision were based on absolute and relative metrics, including intraclass correlation coefficients (ICCs) and Bland-Altman plots.
Results:
Participants walked 628 steps over-ground based on manual counting, and Garmin Vivosmart, Fitbit ONE, and Fitbit Charge had absolute (relative) error values of 6 (0.9%), 8 (1.3%), and 30 (4.4%) steps, respectively. ICC values demonstrated excellent agreement between manually counted steps and steps counted by both the Vivosmart (0.97) and ONE (0.98), but poor agreement for the Charge (0.47). The absolute (relative) precision values for Garmin Vivosmart, Fitbit ONE, and Fitbit Charge were 11.1 (1.8%), 14.7 (2.4%), and 74.4 (12.4%) steps, respectively. ICC confidence intervals demonstrated low variability for the Vivosmart (0.96, 0.99) and ONE (0.93, 0.99), but high variability for the Charge (–0.57, 0.74). The Fitbit ONE maintained high accuracy and precision values for treadmill walking, but both Garmin Vivosmart and Fitbit Charge (the wrist-worn devices) had worse accuracy and precision for treadmill walking.
Conclusions:
The waist-worn sensor (Fitbit ONE) was accurate and precise in measuring steps with over-ground and treadmill walking. The wrist-worn sensors were accurate and precise only during over-ground walking. Such research should inform the application of these devices in clinical research and practice involving PD.
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