Background Hypertension affects 1 in 3 adults worldwide and is a leading cause of death. Most hypertension cases remain undiagnosed, which poses a serious threat to global health. To address this, wearable cuffless devices have been developed to unobtrusively monitor blood pressure (BP), but their accuracy is still undetermined.
Aims To validate a consumer-grade cuffless wearable blood pressure monitor (WBPM, Aktiia), using a medical-grade ambulatory device (ABPM, Mobil-O-Graph), for reference.
Methods 29 participants (20-62 years old, 16 females) simultaneously wore the WBPM and ABPM for 24 hours. The ABPM measured BP every 30 or 60 minutes, during day and night-time, respectively. Readings from the WBPM were automatically taken at rest only. Mean and standard deviation of systolic and diastolic BP were calculated over 24 hours, daytime (06:00-22:00) and night-time (22:00-06:00). Readings were paired if they were taken <10 minutes apart and if the heart rate difference was ≤10 bpm. Summary statistics from participants were compared using bias and limits of agreement (Bland Altman analysis), Pearson's correlation coefficient, and median (interquartile range) of absolute percentage differences.
Results According to the ABMP, 24-hour mean systolic and diastolic BP were 117.1 (109.5, 126.1) and 73.7 (68.7, 80.2) mmHg, respectively, while 24-hour standard deviation of systolic and diastolic BP were 13.0 (10.0, 14.5) and 10.4 (8.2, 13.0) mmHg, respectively. Mean systolic and diastolic BP showed low to moderate correlation (0.27 – 0.41), small biases (~ ±5 mmHg), large limits of agreement (~ ±30 mmHg for systolic and ±20 mmHg for diastolic BP) and median percentage absolute error of ~10%. Agreement for standard deviation of BP was poor. Pairing BP readings before analysis did not significantly improve agreement.
Conclusions This study provides a comprehensive day and night-time comparison between ABPM and a consumer-grade WBPM, informing research into the potential utility of WBPM in hypertension.