JMIR Publications

ABSTRACT

Background:

Wrist-worn devices that incorporate photoplethysmography (PPG) sensing represent an exciting means of measuring heart rate (HR). A number of studies have evaluated the accuracy of HR measurements produced by these devices in controlled laboratory environments. However, it is also important to establish the accuracy of measurements produced by these devices outside of the laboratory, in real-world, consumer use conditions.

Objective:

This study sought to examine the accuracy of HR measurements produced by the Withings ScanWatch during free-living activities.

Methods:

A sample of convenience of seven participants volunteered (three male, four female; age: 64 ± 10 years; height: 164 ± 4 cm; weight: 77 ± 16 kg) to take part in this real-world validation study. Participants were instructed to wear the ScanWatch for a 12-hour period on their non-dominant wrist as they went about their day-to-day activities. A Polar H10 heart rate sensor was used as the criterion measure of HR. Participants used a study diary to document activities undertaken during the 12-hour study period. Activities undertaken during the 12-hour period were classified according to the 11 following domains: desk work; eat/drink; exercise; gardening; household activities; self-care; shopping; sitting; sleep; travel; - walking. Validity was assessed using the Bland-Altman analysis, Spearman's rank correlation coefficient (rs), and mean absolute percentage error (MAPE).

Results:

Overall the ScanWatch produced accurate measurements of HR compared to the Polar H10 with MAPE values < 10% across all activity domains. Moderate to moderately strong correlations (rs = 0.724 -0.891) were observed between devices for all activity domains, except during the walking activity domain which demonstrated a weak correlation (rs = 0.312) between devices.

Conclusions:

The results of this study show that the ScanWatch measures HR with acceptable accuracy during free-living activities in a heterogenous sample of adult volunteers. However, it performed worse during more vigorous activities (e.g. walking, gardening, and household activities) compared to more sedentary activities (e.g. deskwork, eat/drink and sitting). Further larger scale studies examining this device in different populations and during different activities are required before definitive conclusions can be drawn.