The reliability and validity of the four square step test for people with balance deficits secondary to a vestibular disorder

Objective: To determine the reliability and validity of the Four Square Step Test (FSST) for use in people with balance deficits secondary to vestibular disorders, who frequently report falling and have difficulty with changes of direction. Design: Cross-sectional descriptive study. Setting: Outpatient clinic. Participants: Thirty-two people with balance deficits secondary to vestibular disorders (mean age, 63.7 +/- 17.8y) who were currently enrolled in a vestibular physical therapy program agreed to participate. Interventions: Participants performed the FSST, the Timed Up & Go (TUG) test, an 11-m walk test during which walking speed was recorded, and the Dynamic Gait Index (DGI) and completed the Dizziness Handicap Inventory (DHI) and the Activities-Specific Balance Confidence (ABC) Scale. Main Outcome Measures: The main outcome measures were the FSST time, TUG results, DGI score, gait velocity, and DHI and ABC scores. Number of fall risk factors, as determined by published scores for people at risk for falling on the TUG test and gait speed, and number of falls were compared with FSST scores. Results: The FSST has good reliability (intraclass correlation coefficient, model 3,1:.93; 95% confidence interval, .86-.96) and had good correlations with the other gait measures (correlation coefficients for the TUG, .69; gait speed, .65; DGI, -.51) and poor correlations with the DHI and the ABC (DHI, -.13; ABC, -.12). Multivariate linear regression showed that 51.5% of FSST performance was explained by TUG score and gait speed. The mean FSST time differed significantly between groups with 0 (n = 12), 1 (n = 12), or 2 to 3 (n = 8) risk factors for falls (analysis of variance, F=10.02; P <.01). A cutoff score of greater than 12 seconds on the FSST was associated with a sensitivity of 80% and specificity of 92% for the identification of subjects with 1 or more risk factors for falls. Conclusions: The FSST is a reliable and valid tool for measuring the ability to perform multidirectional movements in people with balance deficits secondary to vestibular disorders.