Wearable, cuffless, and portable devices for blood pressure monitoring (2015-2025): a scoping review of technologies, calibration, clinical validation, and regulatory frameworks.

BACKGROUND: Out-of-office blood pressure (BP) monitoring is essential for diagnosing and controlling hypertension. Between 2015 and 2025, wearable devices and portable cuffless platforms emerged that estimate BP without a conventional brachial cuff; their evaluation is complicated by technological heterogeneity, calibration, sensitivity to dynamic conditions, and recent device-specific standards. OBJECTIVE: To map the evidence published between 2015 and 2025 on wearable and portable cuffless devices for BP measurement or estimation, describing form factors, technologies, calibration/recalibration, validation, populations, settings, and standards or regulatory frameworks. METHODS: A scoping review was conducted in accordance with PRISMA-ScR and the Joanna Briggs Institute, using the PCC framework. Sources were searched in PubMed/MEDLINE, Scopus, Web of Science, and Embase, supplemented by device-directed searches and citation chasing. Extraction captured population, device, technology, setting, calibration, standard/protocol, comparator, metrics, limitations, conflicts, and funding. RESULTS: Sixty-three sources were included: 7 standards/consensus/regulatory documents, 1 case study, 6 reviews, and 49 primary studies. Primary evidence covered watches with miniaturized cuffs, wearable or portable cuffless devices, and rings/finger devices. Oscillometric wrist watches were methodologically closer to conventional automated monitors, although limited by positioning requirements, reading errors, and scarce ambulatory evidence. Cuffless devices relied on PPG/PWA, PTT/PAT, tonometry, or multimodal approaches, with calibration/recalibration and proprietary algorithms. Critical gaps persisted in post-calibration stability, dynamic conditions, sleep, treatment, arrhythmias, and special populations. CONCLUSIONS: The 2015-2025 ecosystem shows rapid progress and a transition toward cuffless-specific validation. However, clinical utility depends on intended use, population, calibration/recalibration, and setting. Performance should not be extrapolated across technologies, populations, or contexts.