Psychometric properties of 3-meter backward walk test (3MBWT) in people with Parkinson disease.

ABSTRACT

BACKGROUND AND PURPOSE: The purpose of this study was to investigate the 3-meter backward walk test (3MBWT) in individuals with Parkinson Disease (PD) to determine the following (1) concurrent validity with other gait velocity measures and (2) interrater and intrarater reliability of in-person and video assessment. METHODS: A convenience sample of 25 people with PD participated. Forward gait velocity was measured using a computerized walkway (Zeno Walkway System), the 10-meter walk test (10MWT), and 4-meter walk test (4MWT). Backward gait velocity was measured using the 3MBWT. Concurrent validity was assessed using Pearson's correlations. Reliability was assessed using intra-class correlation coefficients (ICC(2,1)). RESULTS: All relationships between the 3MBWT and gait outcome measures were significant. The 3MBWT demonstrated strong correlations with the 4MWT dual task (r = .795, p=<.001) and moderate correlations with 4MWT comfortable walking speed (r = .658, p < .001), 4MWT fast walking speed (r = .601,p=.002), 10MWT comfortable walking speed (r = .512, p = .009), and 10MWT dual task (r = .535, p = .006). A low yet significant correlation was noted with the 10MWT fast walking speed (r = .398, p = .049). Association between the 3MBWT and the Zeno Walkway System revealed moderate correlations. All reliability tests were significant at p < .001. Interrater reliability ICC(2,1) values were very high for 3MBWT (ICC(2,1) = 0.93, [0.83-0.91]). Intrarater reliability was also very high (ICC(2,1) = 0.96 [0.90-0.98]). CONCLUSION: The 3MBWT demonstrates validity and reliability as a tool for assessing gait speed in the posterior direction in people with PD.