Developing Crosswalks Between Standardized Cross-Setting Section GG Functional Items & Postacute Site-Specific Functional Items

PURPOSE: We developed crosswalks to translate functional scores between standardized functional Section GG and site-specific Functional Independence Measure (FIM^®), allowing functional status to be longitudinally measured over time.

DESIGN: We retrospectively analyzed 100% 2019 CMS administrative claims for patients living with stroke (N=10,140) at inpatient rehabilitation facilities.

METHOD: To reduce unintended coding errors in claims, we first applied the developed algorithm to include only consistent patient responses between Section GG and FIM1. A study comparing three crosswalk approaches recommended Rasch model than expert panel and equipercentile methods2. We thus applied Rasch rating scale model to develop self-care and mobility crosswalks between Section GG and FIM by co-calibrating functional items on the Rasch-Andrich threshold and item step thresholds from the Section GG-FIM item bank. We examined psychometric properties of the item banks and followed the published assessment criteria2 to evaluate translatability of the crosswalks.

RESULTS: The combined Section GG-FIM item bank showed good internal consistency (Cronbach alpha= 0.96 for self-care and 0.97 or mobility). Rasch principal component analysis showed the item bank explained > 40% cutoff (75.9% for self-care and 70.9% for mobility) of total raw variance. Section GG observed and FIM-to-GG crosswalked scores correlated at 0.93 and 0.81 for self-care and mobility, almost identical between Section GG and FIM raw scores, supporting translatability of the crosswalks.

CONCLUSION: Our findings suggested self-care and mobility function item banks can be used as a source for developing the crosswalk to translate functional scores between standardized Section GG and site-specific FIM functional items. Impact Statement: Our findings allow occupational therapists, post-acute policy makers and researchers to translate functional scores before and after the IMPACT Act.

References

Li, C. Y., Mallinson, T., Kim, H., Graham, J., Kuo, Y. F., & Ottenbacher, K. J. (2022). Characterizing Standardized Functional Data at Inpatient Rehabilitation Facilities. Journal of the American Medical Directors Association, 23(11), 1845–1853.e5. https://doi.org/10.1016/j.jamda.2022.02.003

Jones, L. A. T., Li, C. Y., Weitzenkamp, D., Steeves, J., Charlifue, S., & Whiteneck, G. (2021). Development and Validation of Crosswalks Between FIM^® and SCIM III for Voluntary Musculoskeletal Movement Functions. Neurorehabilitation and neural repair, 35(10), 880–889. https://doi.org/10.1177/15459683211033854