Objective: To assess score agreement, validity, precision, and response burden of a prototype computerized adaptive testing (CAT) version of the Mobility Functional Skills Scale (Mob-CAT) of the Pediatric Evaluation of Disability Inventory (PEDI) as compared with the full 59-item version (Mob-59).
Design: Computer simulation analysis of cross-sectional and longitudinal retrospective data; and cross-sectional prospective study.
Setting: Pediatric rehabilitation hospital, including inpatient acute rehabilitation, day school program, outpatient clinics, community-based day care, preschool, and children's homes.
Participants: Four hundred sixty-nine children with disabilities and 412 children with no disabilities (analytic sample); 41 children without disabilities and 39 with disabilities (cross-validation sample).
Interventions: Not applicable.
Main outcome measures: Summary scores from a prototype Mob-CAT application and versions using 15-, 10-, and 5-item stopping rules; scores from the Mob-59; and number of items and time (in seconds) to administer assessments.
Results: Mob-CAT scores from both computer simulations (intraclass correlation coefficient [ICC] range, .94-.99) and field administrations (ICC=.98) were in high agreement with scores from the Mob-59. Using computer simulations of retrospective data, discriminant validity, and sensitivity to change of the Mob-CAT closely approximated that of the Mob-59, especially when using the 15- and 10-item stopping rule versions of the Mob-CAT. The Mob-CAT used no more than 15% of the items for any single administration, and required 20% of the time needed to administer the Mob-59.
Conclusions: Comparable score estimates for the PEDI mobility scale can be obtained from CAT administrations, with losses in validity and precision for shorter forms, but with a considerable reduction in administration time.