Reliability and Minimal Detectable Change for Sit-to-Stand Tests and the Functional Gait Assessment for Individuals With Parkinson Disease

Background And Purpose: This study examined test-retest relative (intraclass correlation coefficient [ICC]) and absolute (minimum detectable change [MDC]) reliabilities for the 5 times sit-to-stand (5×STS), 30-second sit-to-stand (30sSTS), and the functional gait assessment (FGA) tests in people with Parkinson disease (PD). In addition, correlation of these functional tests with a history of falls was examined over a 6-month period, and the internal consistency of the FGA was established.

Methods: Twenty-two patients with PD (Hoehn and Yahr stages 1-3) completed 3 functional tests over 2 test-retest periods of 6 to 8 days. Falls were self-reported for the prior 6 months.

Results And Discussion: Moderate-to-excellent test-retest ICC(2,2) and MDC95 values were found for the 30sSTS (0.94, 3 times) and ICC(2,1) and MDC95 values were found for the FGA (0.86, 4 points). The 5×STS demonstrated a lower ICC(2,2) and a high MDC95 value (0.74, 10 seconds). A significant correlation was only found between past falls and the FGA test (r =-0.48, P < .05) during session 1. Cronbach α values for the 10-item FGA during session 1 and session 2 were 0.75 and 0.85, respectively.

Conclusions: To assess for change over time, we found the 30sSTS and the FGA tests can be used reliably in patients with PD. A lower FGA score was associated with a higher chance of falls, and good internal consistency of the FGA was found.