title: Tracking functional status across the spinal cord injury lifespan: linking pediatric and adult patient-reported outcome scores.
abstract: 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).
  
  
  METHODS
  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.
  
  
  METHODS
  Community.
  
  
  METHODS
  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.
  
  
  METHODS
  Not applicable.
  
  
  METHODS
  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.
authors.affiliation: Boston University School of Public Health, Health & Disability Research Institute, Boston, MA. Electronic address: tianfeng@bu.edu.
authors.forename: Feng
authors.initials: F
authors.lastname: Tian
authors.affiliation: Boston University School of Public Health, Health & Disability Research Institute, Boston, MA.
authors.forename: Pengsheng
authors.initials: P
authors.lastname: Ni
authors.affiliation: Jefferson School of Health Professions, Thomas Jefferson University, Philadelphia, PA.
authors.forename: M J
authors.initials: MJ
authors.lastname: Mulcahey
authors.affiliation: University of Massachusetts, Amherst, MA.
authors.forename: Ronald K
authors.initials: RK
authors.lastname: Hambleton
authors.affiliation: University of Michigan, Ann Arbor, MI.
authors.forename: David
authors.initials: D
authors.lastname: Tulsky
authors.affiliation: Boston University School of Public Health, Health & Disability Research Institute, Boston, MA.
authors.forename: Stephen M
authors.initials: SM
authors.lastname: Haley
authors.affiliation: Boston University School of Public Health, Health & Disability Research Institute, Boston, MA.
authors.forename: Alan M
authors.initials: AM
authors.lastname: Jette
mesh_terms: D000203:Activities of Daily Living; D000293:Adolescent; D000328:Adult; D000367:Age Factors; D000368:Aged; D000369:Aged, 80 and over; D002648:Child; D004185:Disability Evaluation; D005163:Factor Analysis, Statistical; D005260:Female; D006801:Humans; D008297:Male; D008498:Medical Record Linkage; D008875:Middle Aged; D009048:Motor Skills / Q000502:physiology; D011594:Psychometrics; D013119:Spinal Cord Injuries / Q000503:physiopathology*; D015599:Trauma Severity Indices; D016138:Walking / Q000502:physiology; D014910:Wheelchairs; D055815:Young Adult
keywords: Outcome assessment (health care); Psychometrics; Rehabilitation; Spinal cord injuries