Is my smartwatch a valid witness? A systematic review and meta-analysis.
Clinical Snapshot
PICO Framework
| P — Population | Individuals (predominantly healthy adults) wearing commercial smartwatches from four major brands in laboratory and free-living settings |
| I — Intervention | Commercial smartwatch-derived measurements including activity classification, step count, distance, heart rate, energy expenditure, and sleep metrics |
| C — Comparator | Established gold-standard reference measures (e.g., ECG for heart rate, polysomnography for sleep, indirect calorimetry for energy expenditure, research-grade accelerometry for activity/steps) |
| O — Outcomes | Validity and accuracy of smartwatch-derived data across multiple physiological and activity parameters, with secondary relevance to forensic digital evidence applications |
Bottom Line
This systematic review and meta-analysis from the University of Bologna examines whether commercial smartwatches from four major brands produce valid measurements across key physiological and activity parameters, with a novel focus on forensic digital evidence applications. The review's most important finding is also its most honest: the validation evidence base is heterogeneous, methodologically inconsistent, and insufficient to support definitive clinical or forensic practice recommendations. Heart rate monitoring emerges as the most studied and most accurate domain, but quantitative pooled estimates are not reported in the abstract, limiting independent assessment of effect magnitude and precision. The review is predominantly based on healthy adult laboratory populations, which systematically overestimates real-world device performance. Critical methodological gaps — including absent GRADE assessment, no formal heterogeneity quantification, no publication bias analysis, and unclear prospective registration — reduce confidence in the synthesis. For Australian clinicians and forensic practitioners, the key message is clear: smartwatch data should not yet be treated as a reliable standalone clinical or legal data source. The review's greatest value lies in its comprehensive gap analysis and its call for standardised validation protocols, larger and more diverse study populations, and greater manufacturer transparency — a research agenda that is both timely and necessary.
Key Findings
P Value: Not reported in abstract
Effect Size: Not reported in abstract; qualitative conclusion that heart rate was the most accurate measure across brands
Primary Outcome: Validity and accuracy of commercial smartwatch-derived measurements (activity classification, step count, distance, heart rate, energy expenditure, sleep metrics) compared to gold-standard reference measures
Nnt Or Sensitivity: No sensitivity, specificity, accuracy percentages, mean absolute error, or correlation coefficients reported in abstract; quantitative validity metrics not extractable without full text
Confidence Interval: Not reported in abstract
Clinical Application
Commercial smartwatches are widely accessible and low-cost, making implementation feasible in principle. However, the heterogeneous validation evidence means that clinicians and forensic practitioners cannot currently rely on smartwatch data with confidence across all outcome domains. Heart rate monitoring shows the most promise for near-term application. Standardised validation protocols and manufacturer data transparency are prerequisites for broader adoption. In Australia, smartwatches are not listed on the Australian Register of Therapeutic Goods (ARTG) as Class IIa or higher medical devices for most consumer applications, meaning TGA oversight of their clinical accuracy claims is limited. The RACGP does not currently provide specific guidance on the use of consumer wearable data in clinical decision-making. The PBS does not subsidise smartwatch-based monitoring. The Medical Services Advisory Committee (MSAC) has not evaluated smartwatch-derived data as a reimbursable diagnostic modality. From a medicolegal perspective, Australian courts (under the Evidence Act 1995 and state equivalents) would require demonstrated reliability and validity before admitting smartwatch data as forensic evidence — a threshold this review suggests has not yet been met. The Australian Digital Health Agency's national digital health strategy may eventually incorporate validated wearable standards, but current evidence is insufficient to support formal integration. Primarily healthy adults in controlled laboratory settings; limited direct applicability to clinical populations with comorbidities, older adults, or individuals in uncontrolled real-world environments. Forensic applicability requires further validation in ecologically valid settings.
Abstract
Wearable devices are being increasingly used not only in traditional research fields (e.g. clinical, health) but also in innovative ones such as digital forensics. Modern commercial smartwatches, equipped with sensors like accelerometers, gyroscopes, and photoplethysmographs, can record activity, heart rate, sleep, and other physiological parameters that may support forensic investigations, given that their data is valid. To perform a first step in studying such validity, this article presents a systematic review and meta-analysis summarizing the available studies validating data collected from smartwatches, focusing on their potential use in forensic investigations. The review examined studies evaluating smartwatches from four major brands, comparing their outputs, such as activity classification, step count, distance, heart rate, energy expenditure, and sleep metrics, against established gold-standard measures. We found that not all brands of smartwatches and not all outcomes were equally studied, with varying results in terms of accuracy, protocols, and reporting of results. Heart rate resulted the most studied (and most accurate) measure. Most studies validated smartwatches in healthy populations and performed validation in laboratory settings. Overall, while smartwatches show promise for enhancing digital forensic analyses, their current validation evidence is heterogeneous. The findings highlight the need for more extensive and standardized validation efforts, larger and more diverse study populations, and improved transparency from manufacturers. These conclusions are not only relevant for forensic applications but also extend to broader domains, such as clinical and health research, where the reliability of wearable-derived data is equally critical.
References
- 1.Sicbaldi, M., Bartoli, L., Albites-Sanabria, J., D'Ascanio, I., Silvani, A., Chiari, L., Camon, A., & Palmerini, L. (2026). Is my smartwatch a valid witness? A systematic review and meta-analysis. Forensic Science International. https://doi.org/10.1016/j.forsciint.2026.112901
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