Long-term stability and blood pressure change tracking with a cuffless wearable device in hypertensive patients

BACKGROUND: Reliable tracking of short- and long-term blood pressure (BP) changes is a prerequisite for clinical adoption of cuffless BP devices. This study evaluated the 6-week stability of BP estimation by CSEM's wearable photoplethysmography (PPG)-based cuffless BP monitor and its ability to track BP changes in hypertensive patients compared with a validated oscillometric device (Microlife WatchBP Home A). METHODS: In this feasibility method-comparison study, 30 hypertensive patients attended four visits over 6 weeks. At each visit, BP was estimated as the median of 5-7 consecutive measurements obtained with the cuff-based (Cuff BP) and cuffless (PPG BP) devices. Between-visit systolic and diastolic BP changes (ΔSBP, ΔDBP) were compared between devices. Concordance rate (CR), defined as the percentage of significant BP changes (ΔSBP >15 mmHg, ΔDBP >10 mmHg) showing the same direction with both devices, was also assessed. RESULTS: Thirty participants (18 women; age 54 ± 17 years; BMI 29.2 ± 5.5 kg/m²) were included. Differences between devices were 0.2 ± 12.8 mmHg for ΔSBP and -0.1 ± 7.4 mmHg for ΔDBP. No temporal drift in differences between Cuff ΔBP and PPG ΔBP was observed over 6 weeks. CR for significant BP changes was 83% for SBP and 86% for DBP. CONCLUSION: CSEM's wearable cuffless BP monitor provided stable BP estimation and concordant BP tracking during antihypertensive therapy. Interpretation is tempered by substantial variability of the oscillometric reference device. If confirmed in larger studies against a gold-standard reference, these findings could support the clinical acceptance of wearable cuffless BP monitoring.