Evaluating the Discriminant Validity of the Pediatric Evaluation of Disability Inventory: Computer Adaptive Test in Children With Cerebral Palsy

Background. The Pediatric Evaluation of Disability Inventory-Computer Adaptive Test (PEDI-CAT) is a new clinical assessment for children and youth from birth through 20 years of age. Objective. To determine the discriminant validity of the PEDI-CAT according to the Gross Motor Function Classification System (GMFCS) and Manual Ability Classification System (MACS) in children with cerebral palsy (CP). Design. A prospective convenience cross-sectional sample of 101 school-age children with CP was stratified by GMFCS level. Methods. Participants were excluded if they underwent recent surgery (<6 months). Receiver operating characteristics curve analysis was used to quantify the discriminant validity of the PEDI-CAT domains to distinguish the level of independence in fine and gross motor function. General linear modeling was used to assess discriminant ability across all GMFCS and MACS levels. Results. Mean age was 11 years, 11 months (SD 3.7). Mobility and Daily Activities domains exhibited excellent discriminant validity distinguishing between ambulatory and nonambulatory participants [area under the curve (AUC)=0.98 and 0.97, respectively] and the Daily Activities domain exhibited excellent discriminant validity distinguishing between independent and dependent hand function (AUC=0.93). All PEDI-CAT domains were able to discriminate between ambulatory (GMFCS levels I-III) or nonambulatory (GMFCS levels IV-V) as well as manually independent (MACS levels I-II) or manually dependent functional levels (MACS levels III-V) (P < .001). Limitations. Our convenience cross-sectional sample included school-age children with primarily Caucasian, middle-income parents and may not be representative of other cultural, socioeconomic backgrounds. Not all participants had a MACS level assigned, however, no differences were found in PEDI-CAT scores between those with and without MACS scores. Conclusions. These results demonstrate that the PEDI-CAT is a valid outcome instrument for measuring functional abilities in children with CP, able to differentiate across fine and gross motor functional levels.