Concurrent validity and agreement of a virtual reality-based Clinical Testclinical test of Sensory Integrationsensory integration and Balancebalance in middle-aged adults.

BACKGROUND: Sensory integration for postural control relies on dynamic reweighting of visual, somatosensory, and vestibular inputs. The Clinical Test of Sensory Integration and Balance (CTSIB) is widely used, but laboratory-based systems can be costly and less portable. Virtual reality (VR) may provide a scalable alternative, although VR-specific visual features may alter sway behavior and limit interchangeability with traditional protocols. PURPOSE: To evaluate the concurrent validity, agreement, and bias of a VR-based CTSIB (VRCTSIB) relative to a traditional force-plate CTSIB across matched sensory contexts. METHODS: Forty adults aged 40-59 years completed 12 conditions (6 CTSIB, 6 VRCTSIB) during one laboratory session. Matched contexts combined surface (firm, foam) and visual state (normal vision, vision deprivation, sway-referenced/visual perturbation). Outcomes were EllipseArea95, total path length, and radial RMS sway. Validity was assessed with Pearson correlations. Agreement was assessed using ICC(2,1) and Bland-Altman analyses, with proportional bias tested by regressing VRCTSIB - CTSIB differences on the method mean. RESULTS: VRCTSIB and CTSIB were significantly associated across all matched contexts and outcomes (all p < 0.001). Correlations ranged from 0.700 to 0.796 for EllipseArea95, 0.573-0.882 for path length, and 0.542-0.780 for sway. Agreement was condition dependent and lowest in foam eyes-open conditions. Bland-Altman analyses showed context-dependent bias, including notable positive bias in path length during firm eyes-open and foam eyes-open conditions. CONCLUSIONS: VRCTSIB showed evidence of concurrent validity with CTSIB; however, agreement and bias varied across sensory conditions, indicating that the methods should not be considered universally interchangeable without condition-specific calibration or VRCTSIB-specific normative values.