Purpose: Having independent versions of the PROMIS® scales (for Pediatric and Adults) is problematic as scores cannot be evaluated longitudinally as individuals move from childhood into adulthood. The primary aim of this research project is to use item response theory (IRT) to develop a transitional scoring link (or "crosswalk") between the PROMIS adult and pediatric physical health measures.
Setting: Sample 1 was collected at 6 rehabilitation hospitals in the U.S., and participants in Sample 2 were recruited from public health insurance programs and an online research panel.
Methods: PROMIS pediatric and adult physical function, mobility, upper extremity, fatigue, and pain measures were administered to a sample of 874 individuals aged 14-20 years old with special health needs and a sample of 641 individuals aged 14-25 years with a disability. IRT-based scores were linked using a linear approximation to calibrated projection.
Results: Estimated latent variable correlations ranged between 0.84 and 0.95 for the PROMIS pediatric and adult scores. Root Expected Mean Square Difference values were below the 0.08 threshold in all cases except when comparing genders on the Mobility (0.097) and Pain (0.10) scales in the special health care needs sample. Sum score conversion tables for the pediatric and adult PROMIS measures are presented.
Conclusions: The linking coefficients can be used to calculate scale scores on PROMIS adult measures from pediatric measure scores and vice versa. This may lead to more accurate measurement in cross-sectional studies spanning multiple age groups or longitudinal studies that require comparable measurement across distinct developmental stages.
Keywords: Fatigue; Mobility limitation; Pain; Patient-reported outcome measures; Psychometrics; Test equating; Test linking.