Abstract
OBJECTIVE: The purpose of this study was to develop self-report and parent-proxy measures of children's physical activity for clinical research and practice and to demonstrate a valid and reliable instrument of children's lived experience of physical activity as reported by the children themselves or their parent proxies. METHODS: This study involved qualitative development of item pools followed by 2 cross-sectional validity and reliability studies. The National Institutes of Health Patient Reported Outcome Measurement Information System (PROMIS) instrument development standards were applied to create child self-report and parent-proxy physical activity instruments from previously developed, content-valid pools of physical activity items. Each item used a 7-day recall period and had 5 response options. Item bank calibration was based on national samples totaling 3033 children aged 8 to 17 years and 2336 parents of children aged 5 to 17 years. Quantitative analyses included reliability assessments, factor analyses, item response theory calibration, differential item functioning, and construct validation. RESULTS: The final item banks comprised 10 items each. The items were selected based on content and psychometric properties. The item banks appeared to be unidimensional and free from differential item functioning. They showed excellent reliability and a high degree of precision across the range of the latent variable. Child-report and parent-proxy 4- and 8-item fixed-length instruments were specified. The instruments showed moderate correlation with existing self-report measures of physical activity. CONCLUSION: The PROMIS Pediatric Physical Activity instruments provide precise and valid measurement of children's lived experiences of physical activity. IMPACT: The availability of the PROMIS Pediatric Physical Activity instruments will support advances in clinical practice and research that require measurement of pediatric physical activity by self- and parent-proxy report.