Key result
In participants with coronary artery disease, the Fitbit Charge 2 overestimated total protocol energy expenditure by a mean difference of 47.5 kcal compared to the Oxycon Mobile criterion measure.
Why the study?
Commercially available activity trackers are frequently used in cardiac patients, but studies validating their accuracy in this specific population are scarce.
Do wrist-worn activity trackers (Fitbit Charge 2 and Mio Slice) accurately assess energy expenditure compared to indirect calorimetry in patients with CAD and HFrEF?
Observational
Do wrist-worn activity trackers (Fitbit Charge 2 and Mio Slice) accurately assess energy expenditure compared to indirect calorimetry in patients with CAD and HFrEF?
Mean Difference: 47.5
Absolute Event Rate: 275.6% vs 228.1%
Commercially available activity trackers (Fitbit Charge 2 and Mio Slice) demonstrated low accuracy for estimating energy expenditure in cardiac patients, highlighting the need for population-specific algorithms.
Wrist-worn trackers may lack accuracy for energy expenditure in CAD; hypothesis-generating and requires further validation before clinical adoption.
BACKGROUND: Improving physical activity (PA) is a core component of secondary prevention and cardiac (tele)rehabilitation. Commercially available activity trackers are frequently used to monitor and promote PA in cardiac patients. However, studies on the validity of these devices in cardiac patients are scarce. As cardiac patients are being advised and treated based on PA parameters measured by these devices, it is highly important to evaluate the accuracy of these parameters in this specific population. OBJECTIVE: The aim of this study was to determine the accuracy and responsiveness of 2 wrist-worn activity trackers, Fitbit Charge 2 (FC2) and Mio Slice (MS), for the assessment of energy expenditure (EE) in cardiac patients. METHODS: EE assessed by the activity trackers was compared with indirect calorimetry (Oxycon Mobile [OM]) during a laboratory activity protocol. Two groups were assessed: patients with stable coronary artery disease (CAD) with preserved left ventricular ejection fraction (LVEF) and patients with heart failure with reduced ejection fraction (HFrEF). RESULTS: A total of 38 patients were included: 19 with CAD and 19 with HFrEF (LVEF 31.8%, SD 7.6%). The CAD group showed no significant difference in total EE between FC2 and OM (47.5 kcal, SD 112 kcal; P=.09), in contrast to a significant difference between MS and OM (88 kcal, SD 108 kcal; P=.003). The HFrEF group showed significant differences in EE between FC2 and OM (38 kcal, SD 57 kcal; P=.01), as well as between MS and OM (106 kcal, SD 167 kcal; P=.02). Agreement of the activity trackers was low in both groups (CAD: intraclass correlation coefficient [ICC] FC2=0.10, ICC MS=0.12; HFrEF: ICC FC2=0.42, ICC MS=0.11). The responsiveness of FC2 was poor, whereas MS was able to detect changes in cycling loads only. CONCLUSIONS: Both activity trackers demonstrated low accuracy in estimating EE in cardiac patients and poor performance to detect within-patient changes in the low-to-moderate exercise intensity domain. Although the use of activity trackers in cardiac patients is promising and could enhance daily exercise behavior, these findings highlight the need for population-specific devices and algorithms.
No takes yet. Share an insight, caveat, or question.
Herkert et al. (2019) conducted an observational in Coronary artery disease. Fitbit Charge 2 and Mio Slice vs. Oxycon Mobile (Criterion measure) was evaluated on Total protocol energy expenditure (kcal) (MD 47.5). In participants with coronary artery disease, the Fitbit Charge 2 overestimated total protocol energy expenditure by a mean difference of 47.5 kcal compared to the Oxycon Mobile criterion measure.