title: Examining the relationship between medical diagnoses and patterns of performance on the modified Dynamic Gait Index.
abstract: BACKGROUND
  In the original and modified Dynamic Gait Index (mDGI), 8 tasks are used to measure mobility; however, disagreement exists regarding whether all tasks are necessary. The relationship between mDGI scores and Centers for Medicare & Medicaid Services (CMS) severity indicators in the mobility domain has not been explored.
  
  
  OBJECTIVE
  The study objectives were to examine the relationship between medical diagnoses and mDGI scores, to determine whether administration of the mDGI can be shortened on the basis of expected diagnostic patterns of performance, and to create a model in which mDGI scores are mapped to CMS severity modifiers.
  
  
  METHODS
  This was a cross-sectional, descriptive study.
  
  
  METHODS
  The 794 participants included 140 people without impairments (control cohort) and 239 people with stroke, 140 with vestibular dysfunction, 100 with traumatic brain injury, 91 with gait abnormality, and 84 with Parkinson disease. Scores on the mDGI (total, performance facet, and task) for the control cohort were compared with those for the 5 diagnostic groups by use of an analysis of variance. For mapping mDGI scores to 7 CMS impairment categories, an underlying Rasch scale was used to convert raw scores to an interval scale.
  
  
  RESULTS
  There was a main effect of mDGI total, time, and gait pattern scores for the groups. Task-specific score patterns based on medical diagnosis were found, but the range of performance within each group was large. A framework for mapping mDGI total, performance facet, and task scores to 7 CMS impairment categories on the basis of Rasch analysis was created.
  
  
  CONCLUSIONS
  Limitations included uneven sample sizes in the 6 groups.
  
  
  CONCLUSIONS
  Results supported retaining all 8 tasks for the assessment of mobility function in older people and people with neurologic conditions. Mapping mDGI scores to CMS severity indicators should assist clinicians in interpreting mobility performance, including changes in function over time.
authors.affiliation: P.N. Matsuda, PT, PhD, DPT, Department of Rehabilitation Medicine, Division of Physical Therapy, University of Washington, 1959 NE Pacific St, Box 356490, Seattle, WA 98195 (USA). pmatsuda@uw.edu.
authors.forename: Patricia Noritake
authors.initials: PN
authors.lastname: Matsuda
authors.affiliation: C. Taylor, PhD, Measurement, Statistics, and Research Design, College of Education, University of Washington.
authors.forename: Catherine
authors.initials: C
authors.lastname: Taylor
authors.affiliation: A. Shumway-Cook, PT, PhD, FAPTA, Department of Rehabilitation Medicine, Division of Physical Therapy, University of Washington.
authors.forename: Anne
authors.initials: A
authors.lastname: Shumway-Cook
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001930:Brain Injuries / Q000503:physiopathology*; D003430:Cross-Sectional Studies; D005080:Exercise Test; D005260:Female; D005684:Gait / Q000502:physiology*; D020234:Gait Ataxia / Q000503:physiopathology*; D006801:Humans; D008297:Male; D008875:Middle Aged; D051346:Mobility Limitation; D009048:Motor Skills / Q000502:physiology; D010300:Parkinson Disease / Q000503:physiopathology*; 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