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Faculty Advisor(s)

Harold Merriman, PT, PhD, Kurt Jackson, PT, PhD

Description

Purpose/Hypothesis: The Repetitive Step Test (RST) assesses rapid stepping capability in anterior lateral (AL) and posterior lateral (PL) diagonal directions. This study’s goal was to determine the predictive validity of the RST to identify fallers with Parkinson’s Disease (PD). A secondary objective was to determine concurrent validity of the RST to other established tests. It was hypothesized that those who completed fewer steps with the RST would be more likely to fall and that the RST would predict falls at least as well as the other balance tests.

Materials and Methods: 19 subjects (10 F, 9 M; mean age 70.3 years) with mild to moderate PD were tested. Foot dominance was recorded (dominant [Dom] or nondominant [NonD]). The number of steps made by a single leg at 50% and 75% of leg length within 15 seconds were recorded. Data was collected in a single session: RST at 50% and 75%, Timed Up and Go (TUG), Five Time Sit to Stand Test (5TSTS), and 10 Meter Walk Test (10MWT). Falls were then recorded for 6 and 12 months.

Results: ROC curve analysis for the RST, TUG, 5TSTS and 10MWT was performed to determine the area under the curve (AUC) and cut-off scores for sensitivity (Sn) and specificity (Sp) in order to predict future falls. AUCs (0.607-0.762) for the RST were non-significant as were the TUG and 10MWT (p>0.05). AUC for the 5TSTS was significant (0.762 p=0.021) with a cut-off value of 8.0 sec (Sn=0.857, Sp=0.667).

Spearman’s rho correlation was used to compare the tests. RST 50% and RST 75% were analyzed separately in order to assess if one version showed stronger correlations. For the RST 75%, only Dom PL was strongly correlated to 5TSTS (r= -0.71, p=< 0.01). However, Dom AL, NonD AL, and NonD PL of RST 75% were found to be moderately correlated to 5TSTS. All forms of the RST 50% were strongly correlated to 5TSTS (r> -0.72, p=0.01) and all forms of the 50% RST were moderately correlated to the TUG (r> -0.51, p=0.02).

Conclusion: The AUCs for the RST were found to be non-significant, demonstrating poor ability of the RST to predict future falls in patients with PD. However, the 5TSTS was good for fall prediction. All RST 50% directions were strongly correlated with at least one pre-validated balance test, with Dom PL and NonD PL strongly correlating with two established balance tests. This generally supports our hypothesis that the RST 50% would show good concurrent validity with the selected pre-validated tests. The 6 month follow up data was found to be more significant than the 12 month. This could be due to PD being a neurodegenerative disorder and the initial screen not giving good insight on how the patient may perform 12 months later.

Clinical Relevance: Balance and gait measures are important for clinicians treating individuals with PD because they quantify the functional deficits seen in this population. Some tests require a considerable amount of clinic space and/or have a ceiling effect. Our findings support the use of the 5TSTS for fall prediction in persons with PD, but not the RST. However, the RST 75% could be a useful functional tool for identifying specific stepping impairments. The small number of subjects in this study may have impacted our findings.

Publication Date

5-8-2025

Disciplines

Physical Therapy | Rehabilitation and Therapy

Determining the Concurrent and Predictive Validity of the Repetitive Step Test in Individuals With Parkinson’s Disease

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