Responsiveness of evaluative measures for children with cerebral palsy: The Gross Motor Function Measure and the Pediatric Evaluation of Disability Inventory

PURPOSE: The aim of this study is to describe responsiveness of the Gross Motor Function Measure (GMFM) and the Pediatric Evaluation of Disability Inventory (PEDI) in a group of children with cerebral palsy (CP). METHOD: The subjects were 55 children with cerebral palsy aged 2 to 7 years (mean 4.6 years). We described the responsiveness of the GMFM and PEDI for all children (n = 55), for children younger than 4 years of age (n = 22) and those older or equal to 4 years (n = 33). Two frames of references for determining responsiveness were used: change over time and external criterion. Responsiveness was calculated with help of the Effect Size (ES), Standardised Response Mean (SRM) and Spearman rank order correlations of change on both the PEDI and GMFM, with change in motor functioning according to the parents as external criterion. RESULTS: The PEDI has ES and SRM values higher than 0.8. The GMFM has ES and SRM values higher than 0.5. For all dimensions of the PEDI and for almost all dimensions of the GMFM, the ESs and SRMs of the younger group are higher than those of the older group. The ES and the SRM of the GMFM increase with the complexity of the task. When looking at the correlations of the PEDI and GMFM change scores with the opinion of parents, the results are less unequivocal. CONCLUSIONS: Both the GMFM and the PEDI are responsive for change in motor ability over time in children with CP, the most in children younger than 4 years of age.