Validity and reliability of physical functioning computer-adaptive tests for children with cerebral palsy.

Background: The purpose of this study was to assess the concurrent validity and reliability of scores from 4 new parent-report computer-adapted testing (CAT) programs developed to measure the physical functioning of children with cerebral palsy (CP). The Shriners Hospitals for Children CP-CAT battery includes upper-extremity skills, lower-extremity and mobility skills, activity, and global physical health.

Methods: This was a prospective study of 91 children with CP who were tested cross-sectionally and 27 children with CP who were administered the CP-CAT programs twice within approximately a 1-month interval. We examined the concurrent validity of the 4 Shriners Hospitals for Children CP-CAT programs by Pearson correlations with comparative parent-report instruments. The scale reliability was tested by developing estimates of marginal reliability; test-retest reliability was assessed by intraclass correlations.

Results: Pearson correlations were moderate to high in matching content domains of the CATs with the comparison measures. Marginal reliability estimates were always better for the CAT program than the comparative instruments. Average test-retest reliability using Intraclass correlations across the 4 CATs was ICC3,1=0.91 with a range of 0.88 to 0.94.

Conclusions: We found the CAT scores to be related to expected domains from external instruments, to have good scale reliability, and to have stable scores as determined by test-retest reliability. These results support the use of parent-report CATs in the assessment of physical functioning in children with CP.