Construct validity and test-retest reliability of a free mobile application for spatio-temporal gait analysis in Parkinson’s disease patients

Abstract

Background: Mobile applications may be used to assess gait pattern deviation through mobile smartphones in people with Parkinson's disease (PD). However, few studies have investigated their psychometrics properties.

Research question: To study the construct validity and test-retest reliability of the RUNZI® free mobile application in people with mild to moderate PD.

Methods: Thirty individuals were evaluated with the RUNZI® app and with the 10-meter walking test (10 MW), simultaneously. In addition, the Timed Up & Go test (TUG), Tinetti scale, and the Berg Balance Scale (BBS) were used to study the construct validity. Also, test-retest reliability of the mobile for spatio-temporal gait parameters was explored.

Results: The correlation indices of the 10 MW test with the RUNZI® app at fast speeds was moderate to excellent (r = .588-.957). At a comfortable speed, the correlation was excellent for walking speed (r = 0.944), moderate for steps (r = 0.780) and stride length (r = 0.760), and poor for cadence (r = .424). Results showed significant correlations between TUG and spatio-temporal gait parameters at fast and comfortable speeds. There were no significant correlations or consistent associations between Tinetti and BBS and RUNZI®. The test-retest reliability was good to excellent for parameters measured with the RUNZI®.

Significance: Our findings highlight specific opportunities for a free smartphone-based spatio-temporal gait analysis to serve as a complement to conventional gait analysis methods in clinical practice with a moderate to excellent construct validity with the 10 MW test and good to excellent test-retest reliability in PD patients.