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

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.