A study of the validity of the Six-Spot Step Test in ambulatory people with Parkinson's disease

Objective: The aim of this study was to evaluate the concurrent and divergent validity of the Six-Spot Step Test in mild to moderately impaired people with Parkinson's disease. Design: Cross-sectional cohort study. Setting: Outpatient clinics. Subjects: Fifty-eight people with Parkinson's disease. Main measure: The Six-Spot Step Test, the Timed "Up and Go" test, the mini-Balance Evaluation Systems Test (mini-BESTest), and postural sway were tested on the same day, and the Spearman's Rank Correlation Coefficient (rho) was used for data analysis. Results: Subjects had a median age of 68 years (Q1-Q3: 62-73), a median Hoehn and Yahr score of 2.5 (Q1-Q3: 2-3), a median Six-Spot Step Test score of 7.9 seconds (Q1-Q3: 6.5-9.2), a median Timed "Up and Go" test score of 7.0 seconds (Q1-Q3: 5.6-7.9), a median mini-BESTest score of 22.5 (Q1-Q3: 19.8-25.0), and a median postural sway score of 27.9 mm(2) (Q1-Q3: 15.0-53.5) and 22.5 mm/s (Q1-Q3: 14.6-39.8). Statistical significant correlations were found between the Six-Spot Step Test and the Timed "Up and Go" test (rho = 0.81) and the mini-BESTest (rho = -0.64), whereas no significant relations were identified between the Six-Spot Step Test and postural sway (rho = 0.18, P > 0.05). Conclusion: In patients with Parkinson's disease, the Six-Spot Step Test showed promising concurrent validity to other recommended clinical tests for encompassing balance capacity and capacity of functional mobility, making it a reasonable and easily administered alternative to existing assessment tools when measuring walking agility. As expected, weak correlates to postural sway revealed that the Six-Spot Step test is not a valid measure of standing balance.