RT Journal Article SR Electronic T1 Investigating the Validity of the Environmental Framework Underlying the Original and Modified Dynamic Gait Index JF Physical Therapy JO Phys Ther FD American Physical Therapy Association SP 864 OP 870 DO 10.2522/ptj.20140047 VO 95 IS 6 A1 Shumway-Cook, Anne A1 Matsuda, Patricia Noritake A1 Taylor, Catherine YR 2015 UL http://jcore-reference.highwire.org/content/95/6/864.abstract AB Background The modified Dynamic Gait Index (mDGI), developed from a person-environment model of mobility disability, measures mobility function relative to specific environmental demands. The framework for interpreting mDGI scores relative to specific environmental dimensions has not been investigated. Objective The aim of this study was to examine the person-environmental model underlying the development and interpretation of mDGI scores. Design This was a cross-sectional, descriptive study. Methods There were 794 participants in the study, including 140 controls. Out of the total study population, 239 had sustained a stroke, 140 had vestibular dysfunction, 100 had sustained a traumatic brain injury, 91 had gait abnormality, and 84 had Parkinson disease. Exploratory factor analysis was used to investigate whether mDGI scores supported the 4 environmental dimensions. Results Factor analysis showed that, with some exceptions, tasks loaded on 4 underlying factors, partially supporting the underlying environmental model. Limitations Limitations of this study included the uneven sample sizes in the 6 groups. Conclusions Support for the environmental framework underlying the mDGI extends its usefulness as a clinical measure of functional mobility by providing a rationale for interpretation of scores that can be used to direct treatment and infer change in mobility function.