Is the dynamic gait index a useful outcome to measure balance and ambulation in patients with cerebellar ataxia?

Background: Ataxia can adversely affect balance and gait and increase the incidence of falls, which puts individuals at greater risk for injury. Thus, interventions focused on balance and gait are integral in rehabilitation training. In order to determine if rehabilitation interventions are effective, we need an outcome measure to detect change. To our knowledge, no activity level outcome measures have been established for balance and gait in cerebellar ataxia. Objective: The aim of the current study is to determine the reliability and validity of the Dynamic Gait Index (DGI) for ataxia. Design: Twenty adult participants (23–84 years) with ataxia were evaluated to assess construct validity, inter-rater reliability, and same day test-retest reliability of the DGI. Methods: Participants completed ataxia-specific impairment level outcome measures, as well as the DGI. In addition to the in-person rater, three additional physical therapists scored video recordings of DGI test and retests. Construct validity was assessed via Spearman's rank order correlation coefficient (Spearman's rho) between the impairment measures (Scale for Assessment and Rating of Ataxia (SARA), International Cooperative of Ataxia Rating Scale (ICARS) and the DGI. Reliability was assessed by Spearman's rho and Intraclass Correlation Coefficient ICC (2,1). Results: In terms of construct validity, we found significant correlations between the activity level DGI and impairment level outcome measures (-0.81 for SARA; -0.88 with ICARS). The interrater reliability of the DGI applied to participants with ataxia was high (Spearman rho: range 0.71−0.98; ICC (2,1) 0.98) as was test-retest reliability (Spearman rho: 0.95; ICC (2,1) 0.98). Conclusion: We showed that the DGI is a reliable and valid outcome measure to be used in the clinic for individuals with cerebellar ataxia. The DGI had excellent inter-rater and test-retest reliability for raters with varying years of clinical experience. Therefore, the DGI can be a useful clinical outcome measure for assessing balance and ambulation for individuals with cerebellar ataxia.