Construction of the eight-item patient-reported outcomes measurement information system pediatric physical function scales: Built using item response theory

Objective: To create self-report physical function (PF) measures for children using modern psychometric methods for item analysis as part of patient-reported outcomes measurement information system (PROMIS). Study Design and Setting: PROMIS qualitative methodology was applied to develop two PF item pools that comprised 32 mobility and 38 upper extremity items. Items were computer administered to subjects aged 8-17 years. Scale dimensionality and sources of local dependence (LD) were evaluated with factor analysis. Items were analyzed for differential item functioning (DIF) between genders. Items with LD, DIF, or low discrimination were considered for removal. Computerized adaptive testing performance was simulated, and short forms were constructed. Results: Three thousand forty-eight children (51.8% female, 40% nonwhite, and 22.7% chronically ill) participated. At least 754 respondents answered each item. Factor analytical results confirmed two dimensions of PF. Fifty-two of 70 items tested were retained. A 23-item mobility bank and a 29-item upper extremity bank resulted, and an eight-item short forms were created. The item banks have high information from the population mean to three standard deviations below. Conclusions: PROMIS pediatric PF item banks and eight-item short forms assess two dimensions, mobility, and upper extremity function and show good psychometric characteristics after large-scale testing.