A Rasch-Based Comparison of the Functional Independence Measure and Spinal Cord Independence Measure for Outcome and Quality in the Rehabilitation of Persons with Spinal Cord Injury

OBJECTIVE: The Functional Independence Measure (FIM™) and spinal cord injury (SCI)-specific Spinal Cord Independence Measure (SCIM) are commonly used tools for outcome measurement and quality reporting in rehabilitation. The objective of this study was to investigate the psychometric properties of FIM™ and SCIM and to equate the 2 scales. METHODS: First, content equivalence of FIM™ and SCIM was established through qualitative linking with the International Classification for Functioning, Disability and Health (ICF). Secondly, a Rasch analysis of overlapping contents determined the metric properties of the scales and provided the empirical basis for scale equating. Furthermore, a transformation table for FIM™ and SCIM was created and evaluated. SUBJECTS: Patients with SCI in Swiss inpatient rehabilitation in 2017-18. RESULTS: The ICF linking and a separate Rasch analysis of FIM™ restricted the analysis to the motor scales of FIM™ and SCIM. The Rasch analysis of these scales showed good metric properties. The co-calibration of FIM™ and SCIM motor scores was supported with good fit to the Rasch model. The operational range of SCIM is larger than for FIM™ motor scale. DISCUSSION: This study supports the advantage of using SCIM compared with FIM™ for assessing the functional independence of patients with SCI in rehabilitation