Measurement properties of the Spinal Cord Injury-Functional Index (SCI-FI) short forms

Objective: To evaluate the psychometric properties of the Spinal Cord Injury-Functional Index (SCI-FI) short forms (basic mobility, self-care, fine motor, ambulation, manual wheelchair, and power wheelchair) based on internal consistency; correlations between short forms banks, full item bank forms, and a 10-item computer adaptive test version; magnitude of ceiling and floor effects; and test information functions.

Design: Cross-sectional cohort study.

Setting: Six rehabilitation hospitals in the United States.

Participants: Individuals with traumatic spinal cord injury (N=855) recruited from 6 national Spinal Cord Injury Model Systems facilities.

Interventions: Not applicable.

Main outcome measures: SCI-FI full item bank, 10-item computer adaptive test, and parallel short form scores.

Results: The SCI-FI short forms (with separate versions for individuals with paraplegia and tetraplegia) demonstrate very good internal consistency, group-level reliability, excellent correlations between short forms and scores based on the total item bank, and minimal ceiling and floor effects (except ceiling effects for persons with paraplegia on self-care, fine motor, and power wheelchair ability and floor effects for persons with tetraplegia on self-care, fine motor, and manual wheelchair ability). The test information functions are acceptable across the range of scores where most persons in the sample performed.

Conclusions: Clinicians and researchers should consider the SCI-FI short forms when computer adaptive testing is not feasible.