Article

OBJECTIVE: To use item response theory (IRT) methods to link scores from 2
recently developed contemporary functional outcome measures, the adult Spinal
Cord Injury-Functional Index (SCI-FI) and the Pedi SCI (both the parent version
and the child version). DESIGN: Secondary data analysis of the physical
functioning items of the adult SCI-FI and the Pedi SCI instruments. We used a
nonequivalent group design with items common to both instruments and the
Stocking-Lord method for the linking. Linking was conducted so that the adult
SCI-FI and Pedi SCI scaled scores could be compared. SETTING: Community.
PARTICIPANTS: This study included a total sample of 1558 participants. Pedi SCI
items were administered to a sample of children (n=381) with SCI aged 8 to 21
years, and of parents/caregivers (n=322) of children with SCI aged 4 to 21 years.
Adult SCI-FI items were administered to a sample of adults (n=855) with SCI aged
18 to 92 years. INTERVENTIONS: Not applicable. MAIN OUTCOME MEASURES: Five scales
common to both instruments were included in the analysis: Wheelchair, Daily
Routine/Self-care, Daily Routine/Fine Motor, Ambulation, and General Mobility
functioning. RESULTS: Confirmatory factor analysis and exploratory factor
analysis results indicated that the 5 scales are unidimensional. A graded
response model was used to calibrate the items. Misfitting items were identified
and removed from the item banks. Items that function differently between the
adult and child samples (ie, exhibit differential item functioning) were
identified and removed from the common items used for linking. Domain scores from
the Pedi SCI instruments were transformed onto the adult SCI-FI metric.
CONCLUSIONS: This IRT linking allowed estimation of adult SCI-FI scale scores
based on Pedi SCI scale scores and vice versa; therefore, it provides clinicians
with a means of tracking long-term functional data for children with an SCI
across their entire lifespan.
CI - Copyright (c) 2014 American Congress of Rehabilitation Medicine. Published by
Elsevier Inc. All rights reserved.

Langue : ANGLAIS