Spinal cord injury-functional index: item banks to measure physical functioning in individuals with spinal cord injury

Abstract

Objectives: To develop a comprehensive set of patient-reported items to assess multiple aspects of physical functioning relevant to the lives of people with spinal cord injury (SCI), and to evaluate the underlying structure of physical functioning.

Design: Cross-sectional.

Setting: Inpatient and community.

Participants: Item pools of physical functioning were developed, refined, and field tested in a large sample of individuals (N=855) with traumatic SCI stratified by diagnosis, severity, and time since injury.

Interventions: None.

Main outcome measure: Spinal Cord Injury-Functional Index (SCI-FI) measurement system.

Results: Confirmatory factor analysis (CFA) indicated that a 5-factor model, including basic mobility, ambulation, wheelchair mobility, self-care, and fine motor function, had the best model fit and was most closely aligned conceptually with feedback received from individuals with SCI and SCI clinicians. When just the items making up basic mobility were tested in CFA, the fit statistics indicated strong support for a unidimensional model. Similar results were demonstrated for each of the other 4 factors, indicating unidimensional models.

Conclusions: Though unidimensional or 2-factor (mobility and upper extremity) models of physical functioning make up outcomes measures in the general population, the underlying structure of physical function in SCI is more complex. A 5-factor solution allows for comprehensive assessment of key domain areas of physical functioning. These results informed the structure and development of the SCI-FI measurement system of physical functioning.