Validating Virtual Time to Contact With Home Based Technology in Young and Older Adults

Virtual time to contact (VTC) is a measure of postural stability that estimates the virtual time it would take to reach an individual's stability boundary. This study aimed to validate VTC as measured by a depth sensor, and to determine if VTC from the depth sensor distinguishes between older adult fallers and non-fallers compared to a force platform. VTC was assessed in 10 young and 20 older adults by having participants lean in a circular direction followed by five balance tests: eyes open, dual task, eyes open foam, eyes closed, and eyes closed foam. Spearman's correlations and Bland-Altman plots were conducted to determine validity, and Receiver Operating Curves were constructed to discriminate between fallers and non-fallers. Significant correlations were found in the dual task (p = 0.03), eyes open foam (p < 0.01), and eyes closed foam conditions (p = 0.05). The depth sensor discriminated between fallers and non-fallers in the eyes open (p = 0.02), dual task (p = 0.03), and eyes open foam conditions (p = 0.04). VTC was in agreement between the two devices, and VTC derived from a depth sensor and may be used to discriminate between older adult fallers and non-fallers during challenging balance conditions.