Development and Validation of Equations to Link Pediatric Evaluation of Disability Inventory (PEDI) Functional Skills Scores to PEDI-Computer Adaptive Test Scores for Youth with Cerebral Palsy

Abstract

Aim: The Pediatric Evaluation of Disability Inventory (PEDI) was revised to the PEDI-Computer Adaptive Test (PEDI-CAT). The PEDI has been used for over two decades to track function in youth, so it is important that follow-up data are not lost with this transition. The purpose of this study was to develop and validate equations for linking PEDI scores to PEDI-CAT scores.Methods: Caregivers of 101 youth 6.1 to 19.8 years of age with cerebral palsy (CP) and classified at Gross Motor Classification System (GMFCS) Levels I-V completed the PEDI and PEDI-CAT. Scaled score data from this sample were used to develop and validate linking equations using least squares regression and bootstrap cross-validation techniques. Next, equations were tested in an independent sample of 35 children with developmental disabilities.Results: The equations to predict PEDI-CAT scores exhibited excellent model fit. PEDI Self-care, Mobility, and Social Function explained 92%, 84%, and 85% of the variation in PEDI-CAT Daily Activities, Mobility, and Social/Cognitive domains, respectively. No differences were detected between actual and predicted PEDI-CAT scores across all domains and by GMFCS level for the equation development sample and for an equation validation independent sample.Conclusions: The model fit was excellent; however, equations should be used cautiously when evaluating changes in function for individual children with ceiling level PEDI scores. Valid score prediction equations for youth with CP will assist with transitioning from the PEDI to the PEDI-CAT.

Keywords: Cerebral palsy; PEDI; PEDI-CAT; linking equations; score prediction linkage.