The reliability and validity of the 3-m backward walk test in people with Parkinson's disease.

Abstract

People with Parkinson's disease (PwPD) lose the ability in backward walking which is an important part of mobility in daily life. The 3-m backward walk test (3MBWT) evaluates backward walking; however, its reliability and validity have not been examined in PwPD yet. To examine (1) the test-retest reliability of the 3MBWT in PwPD; (2) the minimum detectable change in the 3MBWT times; (3) the concurrent and known-groups validity of the 3MBWT; and (4) the optimum cutoff time which best discriminates fallers from non-fallers with Parkinson's disease (PD). This cross-sectional study included 36 PwPD and 33 healthy people. The 3MBWT was conducted with the 10-m walk test, timed up and go test, Berg Balance Scale, four square step test, activity-specific balance confidence scale, Movement Disorders Society Sponsored Unified Parkinson's Disease Rating Scale, and Hoehn and Yahr Scale. The 3MBWT demonstrated excellent test-retest reliability (ICC = 0.965). The MDC of 2.13s was determined. The 3MBWT had moderate to high correlations with the other outcome measures (correlation coefficient ranged from -0.592 to 0.858). On the 3MBWT times, there were significant differences between PwPD and healthy people, and between fallers and non-fallers with PD (p < 0.001 and p < 0.001, respectively). A 3MBWT time of 10.31s was found to best discriminate fallers from non-fallers with PD. The 3MBWT is a reliable, valid, and easy to administer outcome measure to assess backward walking performance in PwPD, indicating it to be used in practice and research.