Abstract
Objective
To evaluate the content, construct, and discriminant validity of the Narrowing Beam
Walking Test (NBWT), a performance-based balance test for lower limb prosthesis users.
Design
Cross-sectional study.
Setting
Research laboratory and prosthetics clinic.
Participants
Unilateral transtibial and transfemoral prosthesis users (N=40).
Interventions
Not applicable.
Main Outcome Measures
Content validity was examined by quantifying the percentage of participants receiving
maximum or minimum scores (ie, ceiling and floor effects). Convergent construct validity
was examined using correlations between participants’ NBWT scores and scores or times
on existing clinical balance tests regularly administered to lower limb prosthesis
users. Known-groups construct validity was examined by comparing NBWT scores between
groups of participants with different fall histories, amputation levels, amputation
etiologies, and functional levels. Discriminant validity was evaluated by analyzing
the area under each test’s receiver operating characteristic (ROC) curve.
Results
No minimum or maximum scores were recorded on the NBWT. NBWT scores demonstrated strong
correlations (ρ=.70‒.85) with scores/times on performance-based balance tests (timed
Up and Go test, Four Square Step Test, and Berg Balance Scale) and a moderate correlation
(ρ=.49) with the self-report Activities-specific Balance Confidence scale. NBWT performance
was significantly lower among participants with a history of falls (P=.003), transfemoral amputation (P=.011), and a lower mobility level (P<.001). The NBWT also had the largest area under the ROC curve (.81) and was the only
test to exhibit an area that was statistically significantly >.50 (ie, chance).
Conclusions
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.
Keywords
List of abbreviations:
ABC (Activities-specific Balance Confidence), BBS (Berg Balance Scale), CI (confidence interval), FSST (Four Square Step Test), IQR (interquartile range), LLP (lower limb prosthesis), ROC (receiver operating characteristic), TUG (timed Up and Go)To read this article in full you will need to make a payment
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Article info
Publication history
Published online: April 10, 2018
Footnotes
Supported by the National Institutes of Health (award no. K12HD073945) and the Orthotics and Prosthetics Education and Research Foundation (grant no. OPERF-SGA-2016-1).
The content is solely the responsibility of the authors and does not necessarily represent the official views of the National Institutes of Health or the Orthotics and Prosthetics Education and Research Foundation.
Disclosures: none.
Identification
Copyright
© 2018 by the American Congress of Rehabilitation Medicine
