Normative Scores for the Pediatric Evaluation of Disability Inventory in Norway

Aim: The aim of this study was to develop clinically useful normative scores for the Pediatric Evaluation of Disability Inventory (PEDI) for children in Norway, and provide information on the relative difficulty level of individual test items. Methods: Using PEDI protocols from 224 Norwegian children without disability, we computed and scrutinized the normative scores for their representativeness, and compared them with scores from 313 children in the original US PEDI sample. Item functioning was compared using Rasch model-based differential item functioning (DIF) analyses and comparisons of item mastery. Results: The normative scores yielded consistent and regular results. The mean scores for each age group in the Norwegian sample were lower than in their US counterparts, and age mean plots ran parallel. However, this difference may be misleading for clinical use, as item comparisons revealed differences in both higher and lower directions between the samples for about a third of all items. Estimates of relative item difficulty for children in Norway were developed. Conclusions: Identifying potential differences when using an instrument in another culture is important to avoid a risk of over- or underestimating a child's capability. In addition, item response patterns are required to make national normative scores clinically useful.