Responsiveness and Minimal Detectable Change of the Dynamic Gait Index and Functional Gait Index in Persons With Balance and Vestibular Disorders

Background and Purpose: We performed a retrospective chart review to determine the responsiveness and minimal detectable change (MDC95) in persons with balance and vestibular disorders with the dynamic gait index (DGI) and the functional gait assessment (FGA). Methods: The study cohort consisted of 326 patients with a mean age of 60 +/- 18.3 years (range, 18-95 years; 69% female). The DGI, FGA, Activities-Specific Balance Confidence (ABC) scale, and the dizziness handicap inventory (DHI) were collected at intake and discharge. Results: The standardized response mean as an index of responsiveness was greater for the FGA (1.25) than for the DGI (0.72). Both measures demonstrated good internal consistency with baseline measures. The amount of pre- to posttreatment change that exceeds chance variation was estimated at 4 points for the DGI and 6 points for the FGA. In both the DGI and the FGA, a magnitude of change equivalent to the respective MDC95 was significantly associated with improvements in self-reported disability as measured by the ABC and DHI. Discussion and Conclusions: The DGI and the FGA are responsive to change over time in persons with balance and vestibular disorders. More complex gait measures need to be developed, as close to 50% of the subjects received optimal scores at discharge from a physical therapy exercise program, indicating that these measures have a ceiling effect. Video Abstract available (see Video, Supplemental Digital Content 1, http://links.lww.com/JNPT/A70 for more insights from the authors).