Developmental Trajectories for the Early Clinical Assessment of Balance by Gross Motor Function Classification System Level for Children With Cerebral Palsy

Background: Children with cerebral palsy (CP) characteristically present with impairments in balance. Currently, the pattern and timing of the development of balance ability have not been described for children with CP of varying Gross Motor Function Classification System (GMFCS) levels. Objective: The purpose of this study was to document longitudinal developmental trajectories in a measure of balance, the Early Clinical Assessment of Balance (ECAB) scores, along with age-specific reference percentiles and the amount of change typical over a 1-year period for children within different GMFCS levels. Design: The design was a longitudinal cohort study. Methods: Participants included 708 children with CP, aged 18 months through their 12th birthday, and their families. Children participated in 2 to 5 assessments using the GMFCS and ECAB. Results: Longitudinal trajectories describing the average change in the ECAB score with respect to age were created by fitting separate nonlinear mixed-effect models for children in each GMFCS level. Reference percentiles were constructed using quantile regression of ECAB data from the first visit (baseline) and 12-month and 24-month visits. Using these reference points, the amount of change in percentiles was calculated for all children by subtracting the baseline percentile score from the 12-month percentile score. Children whose percentile changes are within the 80% limits can usually be described as "developing as expected" for their age and GMFCS levels. Limitations: Limitations of this study included use of a convenience sample, a ceiling effect of the ECAB for some children in GMFCS levels I and II, and the use of both a 12-month and 24-month study protocol that impacted the number of children available for each assessment session. Conclusions: When used appropriately to monitor development and change over time for children with CP, the ECAB longitudinal trajectories, reference percentiles, and the associated change scores presented here should assist therapists and families in collaborative interaction to proactively plan services and interventions relative to balance ability.