Psychometric properties of a core set of measures of balance for people with cerebellar ataxia secondary to multiple sclerosis

Abstract

Objective: To examine the reliability, validity, and interpretability of 4 clinical measures in assessing the severity of balance dysfunction among people with cerebellar ataxia (CA) secondary to multiple sclerosis (MS). Design: Cross-sectional observation study. Setting: Outpatient clinics. Participants: Consecutive participants with CA secondary to MS (N=60). Interventions: Not applicable. Main Outcome Measures: Balance was assessed and video recorded using the Berg Balance Scale (BBS), timed Up and Go (TUG) test, posture and gait subcomponent of the International Co-operative Ataxia Rating Scale (ICARS), and gait, stance, and sit subcomponents of the Scale for the Assessment and Rating of Ataxia (SARA). The videos were later used to estimate reliability. The Barthel Index, Expanded Disability Status Scale (EDSS), ICARS, and SARA were assessed, and disease duration was recorded. Results: Reliability was good for all 4 measures (intraclass correlation coefficient range, .95–.99). Internal consistency was moderate to good for all 4 measures (α range, .72–.94), with a moderate to good correlation between the measures of balance (Spearman ρ range, .72–.85) and poor to moderate correlation with disease severity (EDSS), functional independence (Barthel Index), and disease duration (Spearman ρ range, –.37 to .76). Minimal detectable change was derived for the BBS (3), posture and gait subcomponent of the ICARS (2), and gait, stance, and sit subcomponents of the SARA (2). Measures were able to discriminate between assistive walking device users and nonusers. Conclusions: All 4 measures showed good reliability and acceptable validity; however, because of the item repetition in scoring of the posture and gait subcomponent of the ICARS and moderate construct, criterion, and convergent validity of the TUG, the BBS and gait, stance, and sit subcomponents of the SARA are recommended for balance assessment in clinical practice for people with CA secondary to MS.