Previously submitted to: Journal of Medical Internet Research (no longer under consideration since Oct 18, 2025)
Date Submitted: Sep 3, 2025
Open Peer Review Period: Sep 4, 2025 - Oct 30, 2025
(closed for review but you can still tweet)
NOTE: This is an unreviewed Preprint
Warning: This is a unreviewed preprint (What is a preprint?). Readers are warned that the document has not been peer-reviewed by expert/patient reviewers or an academic editor, may contain misleading claims, and is likely to undergo changes before final publication, if accepted, or may have been rejected/withdrawn (a note "no longer under consideration" will appear above).
Peer review me: Readers with interest and expertise are encouraged to sign up as peer-reviewer, if the paper is within an open peer-review period (in this case, a "Peer Review Me" button to sign up as reviewer is displayed above). All preprints currently open for review are listed here. Outside of the formal open peer-review period we encourage you to tweet about the preprint.
Citation: Please cite this preprint only for review purposes or for grant applications and CVs (if you are the author).
Final version: If our system detects a final peer-reviewed "version of record" (VoR) published in any journal, a link to that VoR will appear below. Readers are then encourage to cite the VoR instead of this preprint.
Settings: If you are the author, you can login and change the preprint display settings, but the preprint URL/DOI is supposed to be stable and citable, so it should not be removed once posted.
Submit: To post your own preprint, simply submit to any JMIR journal, and choose the appropriate settings to expose your submitted version as preprint.
Warning: This is an author submission that is not peer-reviewed or edited. Preprints - unless they show as "accepted" - should not be relied on to guide clinical practice or health-related behavior and should not be reported in news media as established information.
Smart Ring in Clinical Medicine: A Systematic Review
ABSTRACT
Background:
Smart rings enable continuous physiological monitoring through finger-worn sensors. Despite growing consumer adoption exceeding 2 million users globally, their clinical utility beyond sleep tracking remains unclear.
Objective:
To systematically review evidence for smart ring applications in clinical medicine, assess measurement accuracy, and evaluate clinical outcomes across medical domains.
Methods:
We searched PubMed/MEDLINE, Embase, and Cochrane Library through July 31, 2025, for studies using smart rings in clinical applications. Inclusion criteria: adults ≥18 years, commercially available smart rings, health-related outcomes, and English language. We excluded pure validation studies, device development papers, and pediatric populations. Two reviewers independently screened studies and extracted data. Risk of bias was assessed using ROBINS-I and RoB 2.0.
Results:
From 862 citations, 107 studies met inclusion criteria (85 non-randomized studies, 14 case reports/series, 8 randomized trials) including approximately 100,000 participants. Studies were equally distributed between sleep (n=51, 47.7%) and non-sleep applications (n=56, 52.3%). The Oura Ring dominated research (77 studies, 72.0%). Smart rings demonstrated high accuracy: heart rate r=0.996 versus electrocardiography, heart rate variability (HRV) r=0.980, sleep detection 93-96% sensitivity. Non-sleep applications have demonstrated predictive capabilities across various fields: COVID-19 detected 2.75 days before symptoms (82% sensitivity, 63% specificity, n=63,153); inflammatory bowel disease flares predicted 7 weeks early (72% accuracy); bipolar episodes detected 3-7 days early (79% sensitivity); postoperative pain predicted with 70% accuracy (AUC 0.762). Gastric cancer patients showed 86% HRV reduction versus controls and HRV correlated with tumor size, tumor infiltration, lymph node metastasis and distant metastasis. However, 65% of studies had moderate-to-high risk of bias. Critical limitations included small samples (median 47-89 excluding outliers), proprietary algorithms preventing reproducibility (89% of studies), poor diversity reporting (only 35% reported race/ethnicity), and declining adherence (80% at 3 months to 43% at 12 months).
Conclusions:
Smart rings have evolved beyond sleep tracking, with equal sleep/non-sleep applications confirming transformation into clinical tools capable of early disease detection through autonomic monitoring. Evidence supports use in sleep disorders, mental health monitoring, and chronic disease management. However, single-manufacturer predominance, algorithmic opacity, population homogeneity, and adherence challenges require attention before widespread clinical implementation.
Citation
Request queued. Please wait while the file is being generated. It may take some time.
Copyright
© The authors. All rights reserved. This is a privileged document currently under peer-review/community review (or an accepted/rejected manuscript). Authors have provided JMIR Publications with an exclusive license to publish this preprint on it's website for review and ahead-of-print citation purposes only. While the final peer-reviewed paper may be licensed under a cc-by license on publication, at this stage authors and publisher expressively prohibit redistribution of this draft paper other than for review purposes.