Examining the relationship between medical diagnoses and patterns of performance on the modified Dynamic Gait Index.

Abstract

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. 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. This was a cross-sectional, descriptive study. 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. 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. Limitations included uneven sample sizes in the 6 groups. 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.