AIM: This study examined the item interpretability and rating scale use of the Pediatric Evaluation of Disability Inventory-Patient-Reported Outcome (PEDI-PRO) by young people with developmental disabilities. The PEDI-PRO assesses the functional performance of discrete functional tasks in the context of everyday life situations. METHOD: A two-phase cognitive interview design was implemented with a convenience sample of 37 young people (mean age 19y, SD 2y 5mo; 13 males and 24 females; 68% with intellectual disability) with developmental disabilities. In phase I, 182 item candidates were each reviewed by an average of four young people. In phase II, 103 items were carried forward or revised and each reviewed by an average of seven additional young people. Two raters coded responses for intended item interpretation and performance quality; codes were analysed using descriptive statistics. Qualitative analysis explored young people's self-evaluation process. RESULTS: Items were interpreted as intended by most young people (mean 86%). Young people can use PEDI-PRO response categories appropriately to describe their performance: 94% of positive performance descriptions coincided with a positive response category choice; 73% of negative descriptions coincided with a negative response category choice. Young people interpreted items in a literal manner, and their self-evaluation incorporated the use of supports that facilitate functional performance. INTERPRETATION: The PEDI-PRO's measurement framework appears to support the self-evaluation of functional performance of young people with developmental disabilities.
