Accepted for/Published in: JMIR mHealth and uHealth
Date Submitted: Oct 6, 2020
Date Accepted: Dec 12, 2020
Criterion validity of a wrist-worn activity tracker in laboratory and free-living setting in patients with chronic pain
ABSTRACT
Background:
Physical Activity (PA) is evidently a crucial part of the rehabilitation process for patients suffering from chronic pain. Modern wrist-worn activity tracking devices seemingly have a great potential to provide objective feedback and assist in the adoption of healthy PA behavior by supplying data of energy expenditure expressed as Metabolic Equivalents (METS). However, no studies have been found of any wrist-worn activity tracking devices’ criterion validity in estimating METS, heart rate (HR), or step count in patients with chronic pain.
Objective:
The aim was to determine the criterion validity of wrist-worn activity tracking devices for estimations of METS, HR, and step count in a controlled laboratory setting and free-living settings for patients with chronic pain.
Methods:
In this combined laboratory and field validation study, METS, HR, and step count were simultaneously estimated by a wrist-worn activity tracker (Fitbit Versa), indirect calorimetry (Jaeger Oxycon Pro), and a research-grade hip-worn accelerometer (ActiGraph GT3X) during a treadmill walk at three speeds (3.0, 4.5, and 6.0 km/h) in a laboratory setting. METS and step count were also estimated by the wrist-worn activity tracker in free-living settings for 72 hours. The criterion validity was determined by conventional statistics (ICC and Spearman rho) and graphical plots (Bland-Altman Plots) as well as by Mean Absolute Percentage Error (MAPE). Analysis of Variance (ANOVA) was used to determine any significant systematic differences between estimations.
Results:
A total of 42 patients (76% females), 25-66 years of age, with chronic pain, were included. Results showed that the wrist-worn activity tracking devices (Fitbit Versa) systematically overestimated METS when compared to the criterion measurement (Jaeger Oxycon Pro) and the relative criterion measurement (ActiGraph GT3X). Poor agreement and correlation was shown in estimated METS between Fitbit Versa and both Jaeger Oxycon Pro and ActiGraph GT3X at all treadmill speeds. Estimations of HR emerged with poor to fair agreement during laboratory-based treadmill walks. For step count, the wrist-worn devices showed a fair agreement and fair correlation at most treadmill speeds. In free-living settings, however, the agreement of step count between wrist-worn devices and waist-worn accelerometer was good, and the correlation was excellent.
Conclusions:
The wrist-worn device systematically overestimated METS and showed poor agreement and correlation compared to the criterion measurement (Jaeger Oxycon Pro) and the relative criterion measurement (ActiGraph GT3X), which needs to be considered when used clinically. Step count measured from the wrist, however, seemed to be a valid estimation, suggesting that future guidelines could include such variables in this group with chronic pain. Clinical Trial: Not applicable in this study
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