What do real-world gait related digital mobility outcomes tell us about Parkinson’s disease? A systematic review of the literature

Clinical assessments of Parkinson’s disease (PD) often focus on structured motor tasks, potentially underestimating real-world mobility impairment. Digital mobility outcomes (DMOs) from wearable devices, such as walking speed, offer a promising alternative, but their clinical value remains unclear. This review examined how real-world DMOs are measured and described in PD. A systematic search across eight databases (2000–2024) identified 27 studies investigating 15 DMOs. Studies varied in devices, assessment durations, and walking bout thresholds. Walking speed was the most reported DMO (77%), followed by step length (59%) and stride time (48%). DMOs consistently differed between PD vs controls and real-world vs supervised settings. However, subgroup differences were inconsistent, and associations with motor severity emerged only when DMOs were aggregated across thresholds. Standardised measurement protocol is needed to enhance comparability. DMOs offer unique, ecologically valid insights into PD mobility. Further work is needed to explore establish their predictive capacity and explore more complex DMOs and composite measures. Trial Registration: PROSPERO 2021 CRD42021281213