Virtual Reality Sickness and Safety During Use of a Purpose-Built Seated Virtual Reality System in Clinical Rehabilitation: Retrospective Single-Arm Cohort Study.

Abstract

Virtual reality (VR) sickness is a recognized barrier to the clinical adoption of immersive rehabilitation. Evidence on the tolerability of purpose-built clinical VR systems used at scale remains limited. This real-world feasibility and safety study aimed to describe the frequency of recorded VR sickness in a primary cohort using a purpose-built, seated VR rehabilitation system (mediVR KAGURA®) integrating seven multisensory engineering principles, and to characterize serious adverse events in a secondary post-marketing surveillance (PMS) cohort, without assessing the causal effects of individual features. We conducted a single-arm, retrospective observational cohort study (no comparison group) of two cohorts, following the Journal Article Reporting Standards for quantitative research. The primary cohort comprised all 3572 unique users (patients and general public, aged 3-100 years) identified from company records and server logs between November 2023 and June 2025 at our rehabilitation centers (n=578), institutional demonstrations (n=1715), and academic exhibitions (n=1279); typical exposure was 20-60 minutes at our rehabilitation centers and 5-10 minutes elsewhere. Its primary endpoint was VR sickness (user-reported nausea, dizziness, or malaise during or immediately after a session); secondary endpoints were adverse events such as falls or injuries. The secondary PMS cohort comprised all 337,577 therapeutic sessions (approximately 9306 patients) at 170 medical institutions from 2019 to 2025; its endpoints were serious adverse events and VR sickness requiring medical intervention. Sex and diagnoses were not available. All eligible records were analyzed without exclusions, and no outcome data were missing. Analyses were descriptive (95% confidence intervals [CI] by Wilson score and exact binomial methods); no hypothesis tests were performed. In the primary cohort, 13 of 3572 users (0.36%, 95% CI 0.21%-0.62%) had recorded VR sickness, mostly mild and transient, and 1 user (0.03%, 95% CI 0.005%-0.16%) discontinued a session early. No user required medical intervention, and no falls or injuries were recorded. In the PMS cohort, no serious adverse events or VR sickness requiring medical intervention were reported across 337,577 sessions (exact 95% CI 0%-0.0011%), although mild unreported symptoms cannot be excluded. In this real-world dataset, recorded VR sickness was uncommon and mostly mild with a purpose-built seated VR rehabilitation system, and no serious adverse events or medically attended VR sickness were reported in PMS. Whereas earlier work mainly tested individual design features under controlled conditions, this study documents an integrated multisensory design at scale in routine practice. Because it was uncontrolled and applied all features together, it cannot establish causality, attribute effects to individual features, or support comparison with other systems; the findings are proof-of-concept evidence. They suggest that seated, visually stable, and predictable designs can be deployed safely at scale in clinical rehabilitation and motivate prospective controlled studies with standardized symptom measures. UMIN Clinical Trials Registry UMIN000056624.