Validity of the gait variability index for individuals after a stroke in a chronic stage of recovery

Background: Increased variability in spatiotemporal variables has been demonstrated in individuals after stroke. Gait Variability Index (GVI) has recently been proposed, potentially to be used as a standardized tool for quantifying gait impairment due to spatiotemporal variables. The experience with the GVI in patients after stroke is unknown. Research question: The aim of this study was to investigate the validity of the GVI as an outcome measure of gait disturbance after stroke. Methods: 50 individuals (mean age 60.9 +/- 11.2 years) after stroke at a chronic phase of recovery were included. The control group comprised 50 healthy subjects without gait disorders, matched for age and gender. Data on functional mobility and spatiotemporal gait parameters (BTS Smart system) was collected. Results: The results showed lower mean GVI (mGVI) scores (mean 78.53 +/- 6.12), lower GVI for the affected leg (mean 76.32 +/- 7.98) and for the unaffected leg (mean 80.74 +/- 4.68) in the individuals after stroke compared to the healthy subjects (mean 98.00 +/- 6.32). This was significantly different from the control group mean for both mGVI, affected and unaffected leg - p < 0.001. The GVI for the affected leg and unaffected leg as well as the mGVI were significantly correlated with all clinical measures of functional mobility (0.7 <= R vertical bar < 0.9,0.5 <= vertical bar R vertical bar < 0.7, p < 0.001). Significance: The validity of the GVI appears to be confirmed for individuals after stroke at a chronic stage of recovery. The GVI is lower in individuals after stroke compared to healthy controls. The GVI showed moderate to strong correlations with validated clinical measures of functional mobility. Application of the GVI in the clinical practice will significantly facilitate assessment of gait in individuals after stroke, in comparison to the necessity to interpret a large number of data from 3-dimensional gait analysis.