Measurement properties of the Activities Scale for Kids

The Activities Scale for Kids (ASK) is a self-report measure of childhood p hysical disability, that has excellent reliability (ICC=0.97). The purpose of this study was to assess further the ASK's measurement properties. ASK q uestionnaires were completed by 200 children with musculoskeletal limitatio ns (mean age, 10.1 years). Rasch analyses confirmed that all items measured the same construct and supported aggregation of a summary score. Validity of the ASK was demonstrated by a correlation of 0.81 (P < 0.0001) with pare nt-reported Childhood Health Assessment Questionnaire scores; a significant difference in scores according to clinicians' global ratings of disability (P < 0.0001), and a correlation of 0.92 (P < 0.0001) with clinician-observ ation. The ASK showed minimal ceiling effects, no floor effects, and change d by 1.73 standard deviation units after clinically important change. The A SK is a valid and responsive outcome measure that permits 5- to 15-year-old childrens' physical functioning in the community to be assessed accurately by mail. The quality of this measure will enable clinical studies to measu re outcome not only in a way that is relevant to patients, but also in a wa y that is sensitive to small amounts of change and is practical and inexpen sive. (C) 2000 Elsevier Science Inc. All rights reserved.