Commentary on “Investigation of the Dynamic Gait Index in Children

Abstract

“How should I apply this information?” This article suggests use of a standardized balance assessment, the Dynamic Gait Index (DGI), to describe the balance function of children with mild motor problems. Use of measures, such as the DGI, allows therapists to objectively describe performance and change in functional movement ability of children with motor dysfunction. On the basis of this pilot study, it appears that the DGI is sensitive to differences in the dynamic balance skill of children with and without sensory motor dysfunction. Alsalaheen et al1 used the DGI with a sample of children with concussion and dizziness, following vestibular rehabilitation, and a significant treatment effect was reflected in DGI scores. This further supports the use of the DGI with a pediatric population. The intertester reliability of the total DGI score was good when used with children with typical development (TD) (90%). In children with fetal alcohol spectrum disorder (FASD), intertester reliability of the DGI total score, within 1 point, was slightly less (83%). Test-retest reliability was somewhat lower (ICC = 0.71) for a group of children with and without FASD, but a stronger reliability may have been demonstrated if the test-retest period had been shorter. These data suggest that in populations of children with TD, total scores for the DGI are reliable, but in clinical populations, scores are most reliable within 1 point. “What should I be mindful about in applying this information?” The findings of this pilot study are promising, but the strength of the findings is limited by the small sample size of only 20 children (10 with TD and 10 with FASD), covering a 7-year age range. The age range is an issue when interpreting the findings because children at ages 8 to 9 years present a very different developmental profile than those who are 14 to 15 years old, in cognitive, language, vestibular, and visual system development. Complexity of verbal instructions in the DGI may be problematic for young children. The authors have suggested modifications of the DGI instructions to make them more appropriate, but additional modifications to avoid use of “right” and “left” to indicate a direction may be important. Both the visual and vestibular systems contribute to dynamic balance in children, and the vestibular system may not be fully mature by 8 years of age. Young children and children with sensory motor dysfunction may depend more heavily on the visual system during balance activities. These factors may affect performance on items requiring moving the head while walking. Between 8 and 15 years of age, the onset of puberty may also affect motor performance. It is understood that with the small size of this pilot study, the authors could not compare the performance of the younger and older children, or girls and boys. Future studies should compare the performance of children in the different age groups to examine the effect of age and development on performance of each item on the DGI. Finally, readers should consider if the differences between the groups with FASD and TD were clinically significant. A statistically significant difference in total DGI score was seen between the 2 groups of children, with children with FASD scoring lower on the DGI (mean = 21.4) than those with TD (mean = 23.3). Even though this is approximately a 2-point difference, does it reflect a true difference in performance for these 2 populations? More information is needed related to the error of measurement of the DGI when used with children and the magnitude of change in score that reflects meaningful clinically significant difference. Alsalaheen et al1 reported that a meaningful clinically significant difference for the DGI has not been documented, but a change in score of 3 points seems to reflect meaningful change. Also, readers should consider that the 2 groups of children in this study were matched by age, within 6 months. In this age group, a 6-month age difference may present developmental differences. For this reason, and because of the effect of overall development, it is important to use larger age-matched groups and more closely examine the performance of children in different age groups. Donna J. Cech, PT, DHS, PCS Physical Therapy Program, Midwestern University Downers Grove, Illinois Celine M. Rosati Skertich, PT, MS, PCS Easter Seals DuPage and Fox Valley Region Villa Park, Illinois