Article

The Dynamic Gait Index (DGI) has emerged as a valid indicator of
functional gait abilities for people with balance and vestibular disorders.
Recent Rasch-based analyses have indicated possible concerns for
multidimensionality and a ceiling effect within the DGI.
The aim of this study was to evaluate the DGI in a sample of patients from a dizziness and
balance clinic to determine whether patient features such as dizziness or fall
history influence the measurement characteristics of the DGI. DESIGN: This study
used a retrospective design. METHODS: A sample of 117 patients' charts was
reviewed, and patients were grouped according to a primary impairment of
dizziness only or imbalance and were categorized based on a history of falls. A
one-parameter Rasch-Andrich rating scale model was used with thorough analyses,
including rating scale analysis, item-difficulty hierarchy, scale
unidimensionality, and differential item functioning (DIF). RESULTS: The DGI
demonstrated an effective rating scale design and was found to be a
unidimensional measurement of dynamic gait. The DGI displayed a modest ceiling
effect, primarily with patients with higher functional levels displaying symptoms
of dizziness. Three items ("vertical head nods," "gait on level surface," and
"stepping over obstacles") demonstrated DIF based on categories of patient
characteristics, although the effects on measurement were negligible.
LIMITATIONS: Functional categories were based on impairments and not underlying
medical diagnoses derived from a retrospective chart review, whereas the limited
sample size may have underestimated statistically significant DIF. CONCLUSIONS:
Results from this study offer additional evidence supporting the validity of the
DGI as a measure of gait ability. The present findings also are in agreement with
prior research that has shown a ceiling effect for the DGI in people with balance
or vestibular disorders. Effects of DIF were found to be negligible, yet the
presence of DIF within the present sample helped to explain some differences in
DGI item-difficulty hierarchies from prior studies. Continued research is needed
to determine how population differences may affect performance on the DGI and to
develop and test assessments capable of measuring a broader range of gait abilities.

Langue : ANGLAIS