Psychometric properties of outcome measures evaluating decline in gait in cerebellar ataxia: A systematic review

Cerebellar ataxia often results in impairment in ambulation secondary to gait pattern dysfunction and compensatory gait adjustments. Pharmaceutical and therapy-based interventions with potential benefit for gait in ataxia are starting to emerge, however evaluation of such interventions is hampered by the lack of outcome measures that are responsive, valid and reliable for measurement of gait decline in cerebellar ataxia. This systematic review aimed for the first time to evaluate the psychometric properties of gait and walking outcomes applicable to individuals with cerebellar ataxia. Only studies evaluating straight walking were included. A comprehensive search of three databases (MEDLINE, CINAHL and EMBASE) identified 53 studies meeting inclusion criteria. Forty-nine were rated as 'poor' as assessed by the COnsensus-based Standards for the selection of health Measurement INstruments checklist. The primary objective of most studies was to explore changes in gait related to ataxia, rather than to examine psychometric properties of outcomes. This resulted in methodologies not specific for psychometric assessment. Thirty-nine studies examined validity, 11 examined responsiveness and 12 measured reliability. Review of the data identified double and single support and swing percentage of the gait cycle, velocity, step length and the Scale for Assessment and Rating of Ataxia (SARA) gait item as the most valid and responsive measures of gait in cerebellar ataxia. However, further evaluation to establish their reliability and applicability for use in clinical trials is clearly warranted. We recommend that inter-session reliability of gait outcomes should be evaluated to ensure changes are reflective of intervention effectiveness in cerebellar ataxia.