Establishing content validity of LIMB-Q Kids: a new patient-reported outcome measure for lower limb deformities

Purpose: To establish the content validity of LIMB-Q Kids, a new patient-reported outcome measure (PROM) for children with lower limb deformities. This study focused on three key components of content validity, i.e., comprehension, comprehensiveness, and relevance. Methods: Cognitive debriefing interviews (CDIs) with children with lower limb deformities were performed, and expert input from parents and clinicians directly involved in the care of children with lower limb deformities was obtained. CDIs were conducted with children from sites in Australia, Canada, and the USA. All interviews were recorded and transcribed verbatim. Analyses were conducted using the reparative approach, which involved close examination of the transcribed interviews and summarising edits after each interview. Results: Forty patients, experts, and parents reviewed LIMB-Q Kids and provided feedback. At the start, LIMB-Q Kids had 10 scales and 124 total items. Five rounds of input was obtained from children, parents, and experts. Overall, 37 new items were added. Thirty-three of the new items were included to measure symptoms experienced in different parts of the legs. Final version of LIMB-Q Kids had 11 scales and 159 items. Conclusion: This study established content validity of the LIMB-Q Kids, a new PROM for children with lower limb deformities. An international field-test study is underway. Translation and cultural adaptation are underway for sites where English is not the first language. Scoring algorithms will be developed, following which the scale could be used to inform clinical practice and research.