Feasibility of watch-based blood pressure monitoring device in daily blood pressure monitoring.

Background: Cuffless blood pressure (BP) measurement devices integrated into smartwatches have gained prominence, yet limited studies provide the feasibility and preciseness of daily BP monitoring. Here, we evaluated the trackability of daily BP variance and the precision of the calibration process.

Methods: We collected the data from 896 participants, reporting 35,592 BP values, and body composition analysis data measured by the Samsung Galaxy Watch 6 device. Participants were instructed to measure BP daily, in the morning (5 AM-9 AM) and evening (6 PM-10 PM) for 2 weeks, with initial calibration and re-calibration after the first week. Body composition data, obtained using the Galaxy Watch's bioelectrical impedance analysis sensor, was measured voluntarily during the campaign without specific time constraints.

Results: With BP readings collected using smartwatches, morning and evening BP values showed a significant difference, higher in the evening by 1.42 ± 5.25 mmHg (P < 0.05). Basal metabolic rate, skeletal muscle mass, total body water, morning systolic BP, morning pulse pressure, and morning heart rate were significantly associated with higher difference in morning-evening BP. The calibration stability was assessed by the difference in average BP before and after calibration, showing a substantial pre-post calibration BP difference by 4.64 ± 4.73 mmHg of systolic BP and 3.66 ± 3.62 mmHg of diastolic BP.

Conclusions: In conclusion, watch-based devices may not detect clinical-level BP variability, and substantial extent of pre-post calibration error has to be solved for their utility in regular real-life BP monitoring.