Measuring the Reliability and Construct Validity of the Pediatric Evaluation of Disability Inventory - Computer Adaptive Test (PEDI-CAT) in Children with Cerebral Palsy.

OBJECTIVE: The purpose of this study was to (1) investigate the construct validity and (2) test-retest reliability of the Pediatric Evaluation of Disability Inventory - Computer Adaptive Test (PEDI-CAT) in children with cerebral palsy (CP).

DESIGN: A prospective convenience cross-sectional sample SETTING: Multidisciplinary CP clinic in a tertiary level pediatric children's hospital PARTICIPANTS: One hundred and one, English and Spanish speaking school aged children with a diagnosis of CP, stratified by Gross Motor Function Classification System level, who presented to our multidisciplinary clinic. Participants were excluded if they underwent recent surgery (<6months) or Botulinum Neurotoxin A injection (<3months). A subset of seventeen families participated in retest reliability.

MAIN OUTCOME MEASURES: Convergent and divergent validity were evaluated using Spearman's correlation analysis; test-retest reliability was assessed using intraclass correlation coefficients (ICC).

RESULTS: Mean age was 12 years (SD=3.7). Convergent validity was established between Mobility (PEDI-CAT) and Functional Mobility Scale (FMS) (5m, r=0.85; 50m, r=0.84; 500m, r=0.76; p<0.001). In ambulant children, convergent validity was established between Daily Activities (PEDI-CAT versus Pediatric Quality of Life CP (PedsQL-CP) (r=0.85, p<0.001) and between Social/Cognitive (PEDI-CAT) and Speech and Communication (PedsQL-CP) (r=0.42; p<0.001). In non-ambulant children, convergent validity was established between Daily Activities (PEDI-CAT) and Personal Care [Caregiver's Priority and Child Health Index of Life with Disabilities - (CPCHILDTM )] (r=0.44, p<0.001) and between Social/Cognitive (PEDI-CAT) and Communication (CPCHILDTM ) (r=0.64; p<0.001). A lack of correlation between Daily Activities, Social/Cognitive, and Responsibility (PEDI-CAT) and FMS and between the Mobility (PEDI-CAT) and Communication (PedsQL) domains confirmed divergent validity. Test-retest reliability was excellent for all domains of the PEDI-CAT (ICC=0.96-0.99).

CONCLUSIONS: The PEDI-CAT is an outcome measure which demonstrates strong construct validity and reliability in children with CP.