Validation and Subgroup Analysis of the Accuracy of the Photoplethysmography-based Microlife Cuffless Upper-arm Wearable Blood Pressure Monitor

BACKGROUND: This study (1) validates the accuracy of the photoplethysmography-based Microlife cuffless upper-arm wearable blood pressure (BP) monitor according to the AAMI/ESH/ISO 81060-2:2018/Amd 1:2020 standard; (2) investigates the device's performance across age groups and skin tone; and (3) evaluates the advantages of cuffless BP monitoring in terms of estimation variability, required time, and stability. METHODS: A total of 120 participants aged ≥20 years were recruited from the general population, ensuring the representation of diverse age and skin tone groups. The device was calibrated against a clinically validated mercury sphygmomanometer. Sequential same-arm BP estimation were performed. Accuracy was analyzed according to the ISO criteria, and further subgroup analysis was conducted to compare results between participants aged ≥65 and <65 years, as well as between participants with lighter and darker skin tones (classified according to the Fitzpatrick system). Additionally, estimation stability and variability were evaluated using 3 averaged BP estimations. RESULTS: The results demonstrated that the Microlife device met the AAMI/ESH/ISO accuracy criteria. Subgroup analysis revealed consistent accuracy across age and skin tone groups, with slight differences warranting further exploration. Notably, the cuffless design enabled faster estimations with reduced variation between the 3 averaged readings, showcasing its potential for home BP monitoring and frequent self-assessments. CONCLUSIONS: These findings support the clinical potential of photoplethysmography-based cuffless BP monitoring in diverse adult populations, particularly for facilitating rapid and stable BP estimations in elderly individuals and users with varying skin tones. Further large-scale studies are warranted to corroborate and build upon these observations.