title: Investigating the validity of the environmental framework underlying the original and modified Dynamic Gait Index.
abstract: 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.
  
  
  METHODS
  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.
  
  
  CONCLUSIONS
  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.
authors.affiliation: A. Shumway-Cook, PT, PhD, FAPTA, Department of Rehabilitation Medicine, Division of Physical Therapy, University of Washington, 1959 NE Pacific St, Box 356490, Seattle, WA 98195 (USA). ashumway@uw.edu.
authors.forename: Anne
authors.initials: A
authors.lastname: Shumway-Cook
authors.affiliation: P.N. Matsuda, PT, PhD, DPT, Department of Rehabilitation Medicine, Division of Physical Therapy, University of Washington.
authors.forename: Patricia Noritake
authors.initials: PN
authors.lastname: Matsuda
authors.affiliation: C. Taylor, PhD, College of Education, University of Washington.
authors.forename: Catherine
authors.initials: C
authors.lastname: Taylor
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001930:Brain Injuries / Q000503:physiopathology; D003430:Cross-Sectional Studies; D004777:Environment; D005080:Exercise Test; D005163:Factor Analysis, Statistical; D005260:Female; D005684:Gait / Q000502:physiology*; D020234:Gait Ataxia / Q000503:physiopathology; D006801:Humans; D008297:Male; D008875:Middle Aged; D051346:Mobility Limitation; D008962:Models, Theoretical; D009048:Motor Skills / Q000502:physiology*; D010300:Parkinson Disease / Q000503:physiopathology; D011187:Posture / Q000502:physiology; D012720:Severity of Illness Index; D020521:Stroke / Q000503:physiopathology; D013647:Task Performance and Analysis; D013997:Time Factors; D015837:Vestibular Diseases / Q000503:physiopathology; D016138:Walking / Q000502:physiology; D055815:Young Adult