D.C. Dye, PT, PhD, Department of Physical and Occupational Therapy, School of Rehabilitation and Communication Sciences, Idaho State University, Mailstop 8045, Pocatello, ID 83209 (USA).
Phys Ther. 2013 Jun;93(6):809-18. doi: 10.2522/ptj.20120163. Epub 2013 Feb 28.
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.
This study used a retrospective design.
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).
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.
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.
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.
动态步态指数（DGI）已成为评估平衡和前庭障碍患者功能性步态能力的有效指标。最近基于 Rasch 的分析表明，DGI 可能存在多维性和天花板效应的问题。
本研究旨在评估眩晕和平衡诊所患者样本中的 DGI，以确定患者的特征（如头晕或跌倒史）是否会影响 DGI 的测量特性。
本研究采用回顾性设计。
回顾了 117 例患者的病历，根据头晕或不平衡的主要损伤将患者分组，并根据跌倒史进行分类。使用单参数 Rasch-Andrich 评分量表模型进行了全面分析，包括评分量表分析、项目难度层次、量表单维性和差异项目功能（DIF）。
DGI 具有有效的评分量表设计，是动态步态的多维测量。DGI 显示出适度的天花板效应，主要表现为功能水平较高的患者出现头晕症状。基于患者特征的类别，有三个项目（“垂直点头”、“在水平表面行走”和“跨过障碍物”）表现出 DIF，但对测量的影响可以忽略不计。
功能类别基于损伤，而不是从回顾性病历中得出的潜在医学诊断，而且样本量有限可能低估了具有统计学意义的 DIF。
本研究结果为 DGI 作为步态能力测量工具的有效性提供了额外的证据。本研究结果与先前研究一致，表明 DGI 在平衡或前庭障碍患者中存在天花板效应。发现 DIF 的影响可以忽略不计，但本研究样本中存在 DIF 有助于解释 DGI 项目难度层次与先前研究的差异。需要进一步研究确定人群差异如何影响 DGI 的表现，并开发和测试能够测量更广泛步态能力的评估方法。
Zotero 插件