PROMIS Physical Function Item Bank

The PROMIS Physical Function item bank is a large, item-response-theory-calibrated collection of self-reported questions about physical functioning and mobility, developed under the United States National Institutes of Health Patient-Reported Outcomes Measurement Information System initiative. Rather than being a fixed questionnaire, it is a bank of items all placed on a single underlying continuum, so that any subset of items measures the same construct on the same metric. Rose and colleagues' 2008 evaluation of the preliminary bank demonstrated the expected advantages of this approach, and Cella and colleagues' 2010 report described the calibration of PROMIS's first wave of adult item banks. The items are calibrated with a graded response model and anchored to a T-score metric with a mean of 50 and a standard deviation of 10 in the United States general population. Because every item sits on the common metric, the bank supports both fixed short forms and computerized adaptive testing, letting researchers and clinicians measure physical function precisely with relatively few questions and compare scores across studies and instruments.