The PROMIS Physical Function item bank was calibrated to a standardized metric and shown to improve measurement efficiency.
OBJECTIVE
To document the development and psychometric evaluation of the Patient-Reported Outcomes Measurement Information System (PROMIS) Physical Function (PF) item bank and static instruments.


METHODS
The items were evaluated using qualitative and quantitative methods. A total of 16,065 adults answered item subsets (n>2,200/item) on the Internet, with oversampling of the chronically ill. Classical test and item response theory methods were used to evaluate 149 PROMIS PF items plus 10 Short Form-36 and 20 Health Assessment Questionnaire-Disability Index items. A graded response model was used to estimate item parameters, which were normed to a mean of 50 (standard deviation [SD]=10) in a US general population sample.


RESULTS
The final bank consists of 124 PROMIS items covering upper, central, and lower extremity functions and instrumental activities of daily living. In simulations, a 10-item computerized adaptive test (CAT) eliminated floor and decreased ceiling effects, achieving higher measurement precision than any comparable length static tool across four SDs of the measurement range. Improved psychometric properties were transferred to the CAT's superior ability to identify differences between age and disease groups.


CONCLUSIONS
The item bank provides a common metric and can improve the measurement of PF by facilitating the standardization of patient-reported outcome measures and implementation of CATs for more efficient PF assessments over a larger range.
Department of Quantitative Health Sciences, University of Massachusetts Medical School, Worcester, MA, USA; Department of Psychosomatic Medicine, Medical School, Charité Universitätsmedizin Berlin, Berlin, Germany. Electronic address: rose@charite.de.
Matthias
M
Rose
National Research Centre for the Working Environment, Copenhagen, Denmark; i3 QualityMetric Incorporated, Lincoln, RI, USA; Institute of Public Health, University of Copenhagen, Denmark.
Jakob B
JB
Bjorner
Department of Quantitative Health Sciences, University of Massachusetts Medical School, Worcester, MA, USA.
Barbara
B
Gandek
Department of Immunology and Rheumatology, Stanford University School of Medicine, Palo Alto, CA, USA.
Bonnie
B
Bruce
Department of Immunology and Rheumatology, Stanford University School of Medicine, Palo Alto, CA, USA.
James F
JF
Fries
Department of Quantitative Health Sciences, University of Massachusetts Medical School, Worcester, MA, USA; John Ware Research Group, Worcester, MA, USA.
John E
JE
Ware
D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002138:Calibration; D004185:Disability Evaluation; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D011594:Psychometrics; D036301:Qualitative Research; D015203:Reproducibility of Results; D011795:Surveys and Questionnaires; D055815:Young Adult
Computerized adaptive test; Health status; Item response theory; Patient-reported outcomes; Physical function; Questionnaire