Validity of the gait variability index in older adults: effect of aging and mobility impairments.

Gait variability, defined as the fluctuation in spatiotemporal characteristics between steps, is suggested to be a sensitive indicator of mobility deficits with aging and pathological processes. A challenge in quantifying gait variability is the decision of which spatiotemporal parameters to assess because gait parameters may exhibit different amounts of variability and may differentially relate to mobility performance. The Gait Variability Index (GVI), a composite measure of variability across several gait parameters, was previously developed to overcome this challenge. The present study seeks to validate the use of GVI in the older adult population. A retrospective analysis of gait and clinical data was conducted using data pooled from five prior studies. The final data set included 105 younger adults (YA, age<65) and 81 older adults (OA, age≥65). The GVI of OA (91.92±8.75) was significantly lower compared to the GVI of YA (100.79±7.99). Within OA, the GVI was significantly lower (p<0.0001) in individuals with mobility deficits (84.35±9.03) compared to those with high mobility function (96.35±8.86). Furthermore, GVI was associated with mobility function, including walking speed and performance on the Berg Balance Scale. Our findings imply that the GVI is a valid assessment for gauging spatiotemporal gait variability in older adults, is sensitive to differentiate between high-functioning older adults and those with mild to moderate mobility deficits and is associated with some clinical measures of functional mobility and balance.