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.