Validation of the Narrowing Beam Walking Test in Lower Limb Prosthesis Users

Abstract

The results provide strong evidence of content, construct, and discriminant validity for the NBWT as a performance-based test of balance ability. The evidence supports its use to assess balance impairments and fall risk in unilateral transtibial and transfemoral prosthesis users.

Using Clinical Balance Tests to Assess Fall Risk among Established Unilateral Lower Limb Prosthesis Users: Cutoff Scores and Associated Validity Indices

“…Falls among LLP users frequently lead to adverse health outcomes including injury 3,5,7,9,10 , financial costs 11 , reduced mobility 12,13 , and diminished quality of life 14 . A major barrier to reducing falls among LLP users has been effective screening of those at risk 15,16 . Central to this barrier is a scarcity of LLP user-specific cutoff scores and validity indices for contemporary clinical balance instruments such as the Berg Balance Scale (BBS) 17 , Timed Up and Go (TUG) 18 , Four Square…”

“…Step Test (FSST) 19 , and Activities-specific Balance Confidence (ABC) scale 20 . A number of studies have assessed the validity and reliability of these instruments among LLP users 15,16,[21][22][23][24][25][26][27] , but cutoff scores to infer fall risk have only been established for transtibial prosthesis users with limited prosthetic experience (i.e., 6 months of prosthetic use) 21 . Clinicians therefore, lack the necessary information to This article is protected by copyright.…”

“…Two different faller classifications, either e 1 fall 3,16,28,29 or e 2 falls 3,15,21 have been used to assess the diagnostic accuracy and validity indices of performance-based clinical balance tests. Validity indices for one performance-based balance test, the Berg Balance Scale (BBS), increased when a classification of e 2 falls was used in a prior study 8 .…”

“…The objective of this study was therefore to establish cutoff scores, and associated validity indices, for clinical balance tests administered to established unilateral LLP users. In prior studies it was found that single-task tests like the FSST, TUG, or Narrowing Beam Walking Test (NBWT) demonstrated better discriminant validity than multi-item tests like the BBS, ABC, or the Locomotor Capabilities Index 16,21 . Based on this prior research therefore, it was hypothesized that the validity indices (e.g., likelihood ratios) associated with cutoff scores for the FSST, TUG, and the NBWT would exceed those of the BBS or ABC scale.…”

“…Further, cutoff scores and related validity indices would provide clinicians with the information needed to appropriately interpret clinical balance test scores to assess fall risk in their patients who use LLPs. Owing to the variety of ways researchers and clinicians can classify individuals as fallers or non-fallers 3,15,16,21 , a secondary objective of this study was to determine whether cutoff scores and associated validity indices differed across two common fall classifications (i.e., e 1 fall versus e 2 falls over the past 12 months). It was hypothesized that classifying fallers as e 2 falls would increase validity indices 8 .…”