Does the Minimal Detectable Change in the 10-Meter Walk Test and Timed Up and Go Test Differ by Parkinson's Disease Severity?

OBJECTIVE

To determine the minimal detectable change (MDC) of the 10-meter walk test (10MWT) and Timed Up and Go test (TUG) across different stages of Parkinson's disease (PD) severity as classified by the Hoehn & Yahr scale (H&Y).

DESIGN

Cross-sectional observational study with a repeated-measures design. Subjects completed 2 trials of each test in a single session to assess reliability and MDC95.

SETTING

Inpatient neuromodulation center at a general hospital.

PARTICIPANTS

A total of 80 patients with PD admitted to the Center for Neuromodulation, Kurashiki Heisei Hospital, were categorized into H&Y stage II (n=25), III (n=31), and IV (n=24).

INTERVENTIONS: Not applicable.

MAIN OUTCOME MEASURE(S): The 10MWT and TUG were conducted twice in the "On" medication state. Intraclass correlation coefficients (ICC) and Bland-Altman analyses were used to assess reliability and systematic bias, and MDC95 values were calculated.

RESULTS

Both tests demonstrated high reliability (ICC1,1 > 0.92). MDC95 values for the 10MWT were 0.7 seconds (stage II), 0.9 seconds (stage III), and 1.4 seconds (stage IV). MDC95 values for the TUG were 0.9 seconds (stage II), 1.3 seconds (stage III), and 2.7 seconds (stage IV), indicating greater variability in advanced stages.

CONCLUSIONS

The MDC95 values of 10MWT and TUG increase with PD severity, highlighting the need for stage-specific criteria in clinical assessments. Using severity-specific MDC values may improve the accuracy of treatment evaluations and clinical decision-making in patients with PD.