Assessing Timed Up and Go in Parkinson's disease: Reliability and validity of Timed Up and Go Assessment of biomechanical strategies

Abstract

Objective: To investigate the measurement properties of the Timed Up and Go Assessment of Biomechanical Strategies (TUG-ABS) to determine its adequacy for use with individuals with Parkinson's disease.

Subjects: Fifty individuals with Parkinson's disease.

Design: Diagnostic accuracy.

Methods: The study investigated the following properties: reliability (inter-examiner, intra-examiner, test-retest, internal consistency and minimal detectable change), construct validity, and floor and ceiling effect.

Results: Considering the total score, the inter-examiner, test-retest and intra-examiner reliabilities were classified as excellent (0.95 ≤ intra-class correlation coefficient (ICC)≤0.99). The TUG-ABS presented excellent internal consistency (α = 0.98). The minimal detectable change was 3.82 points. The construct validity between the TUG-ABS and the Unified Parkinson's Disease Rating Scale (UPDRS) - part III was classified as moderate (ρ = -0.62). Significant, elevated and positive correlations were obtained between TUG-ABS and the Balance Evaluation System Test (BESTest)-VI (ρ = 0.72) and negative correlations between TUG-ABS and TUG (ρ = -0.78). The discriminant function obtained with the total score of TUG-ABS classified 60% of the individuals correctly with respect to the group (determined by the performance in TUG) to which they belonged. One-way analysis of variance (ANOVA) showed that TUG-ABS discriminated the individuals with Parkinson's disease in all stages according to Hoehn & Yahr. There was a ceiling effect of 22%.

Conclusion: TUG-ABS presented adequate measurement properties in individuals with Parkinson's disease.