Agreement between Fitbit Versa 4 and a reference standard on time-domain nocturnal heart rate variability: A pilot...

Area of Science:

• Physiology
• Biomedical Engineering
• Wearable Technology

Background:

• Reduced heart rate variability (HRV) is linked to autonomic nervous system (ANS) imbalances affecting overall health.
• Consumer wearables offer HRV measurement, but their clinical reliability is often unverified.
• This study validates Fitbit Versa 4's nocturnal HRV accuracy against a gold standard.

Purpose of the Study:

• To evaluate the Fitbit Versa 4's ability to measure nocturnal heart rate variability (HRV).
• To compare Fitbit Versa 4 HRV data against a reference ambulatory ECG device (Firstbeat Bodyguard 3).
• To assess the reliability and agreement of consumer wearable HRV measurements.

Main Methods:

• Eight participants simultaneously used Fitbit Versa 4 and Firstbeat Bodyguard 3 for at least three nights.
• Nocturnal HRV was quantified using the root mean square of successive differences (RMSSD).
• Statistical analyses included t-tests, Linear Mixed Models, and Bland-Altman analysis.

Main Results:

• Median RMSSD values from Fitbit and Firstbeat were not significantly different (p=0.3858).
• Fitbit measurements averaged 92.3% of the reference Firstbeat measurements.
• Analysis indicated strong correlation and acceptable agreement between the two devices.

Conclusions:

• The Fitbit Versa 4 demonstrates strong correlation and acceptable agreement with ECG-derived HRV measurements.
• Preliminary evidence supports the use of Fitbit Versa 4 for nocturnal HRV monitoring outside laboratory settings.
• Consumer wearables show potential as accessible tools for assessing ANS function.