Article Summary: Psychometric Properties of the Pediatric Balance Scale Using Rasch Analysis
Background: The Pediatric Balance Scale (PBS) measures functional balance and was designed for the school age population. Functional balance is defined by the PBS as “the ability of a child to attain and maintain upright control during typical childhood activities of daily living, school, and play”. The purpose of the PBS is to identify children without age-appropriate balance which may be related to developmental delay or decreased safety, and then objectively track changes in balance due to intervention, maturation or regression.
Purpose: The purpose of this study was to investigate the validity of the PBS to different age groups of children in order to identify and treat balance disorders most effectively by physical therapists.
Study Population:
13 studies (from 1994 to 2011) including 823 children, aged 2 to 13 years, were retrospectively analyzed with uni- and multidimensional Rasch partial credit models. The inclusion criteria in common with these 13 studies was the ability to follow directions with one step and to stand for 4 seconds without assistance.
Methods: This is retrospective RACH analysis of 13 studies of children 2-13 years old from 2009 to 2011. 33 physical therapy students and faculty with at least 20 hours of training each collected the data over 14 years.
Outcome Measures: The (PBS) pediatric balance scale was investigated and found to have concurrent validity with the Peabody Developmental Motor Scales, 2nd Edition and the Bruininks Oseretsky Test of Motor Proficiency, 2nd Edition.
Intervention: Interventions to improve balance were a part of the changes tracked in the PBS score, but the specifics of these interventions, as well as their effectiveness, varied between studies.
Results: This statistical analysis showed that the PBS outcome measure was most effective in measuring functional balance of preschool aged children and could be used as a tool to identify children with mild to moderate balance impairments from those developing typically. Due to the ceiling effect, the applicability of the PBS to school aged children is only to identify moderate balance impairments only.
It was found that the PBS better measured overall functional balance and not a previous 3 category system as sometimes used before.
The most difficult items on the PBS were found to be Standing on One Foot, Standing One Foot in Front, and Reach forward. Some of the items may have a floor effect including: Sitting to Standing, Standing to sitting, Transfers, Sitting Unsupported, Turning to Look Behind and Retrieving Object from Floor. The study recommended adding items testing higher levels of function in order to be more applicable to a wider age range of children.
Strengths:
- Large sample size
- Multiple outcome measures
- All raters had over 20 hours of experience
- Excellent inter-rater reliability
Limitations:
- Some of the data collectors were PT students with less experience
- Different inclusion/exclusion criteria between studies
- Ceiling effect for school age children
Conclusion: The PBS is a valid and recommended measure of functional balance for preschool aged children due to the familiarity of the items tested, minimum equipment and time, and ease of performing and scoring.
This study used Rasch analysis to look at the validity of the PBS and found that it could identify mild and moderate balanced impairments in preschool children less than 6 years old, but only mild impairments in school aged children. It also found that this is a valid outcome measure to track changes in functional balance in the child. Changes of 10 points or more were found to be significant in the balance of a child with cerebral palsy. This study further established the validity of the PBS through concurrent and discriminant validity, establishing a change score, and Rasch analysis. The total test score should be used and not broken into components.
Reference Article:
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Darr N, Franjoine MR, Campbell SK, Smith E. Psychometric properties of the pediatric balance scale using rasch analysis. Pediatric physical therapy. 2015;27(4):337-348. doi:10.1097/PEP.0000000000000178.
Hey Bailey, if the PBS doesn’t really identify impairments in kids older than 6 years, what would you recommend?
I would recommend the GMFM-88 for children with Downs syndrome. It is for validated for children 5 months to 16 years. The GMFM-66 can be used for children with Cerebral Palsy