title: Validity and reliability of the FIM instrument in the inpatient burn rehabilitation population.
abstract: OBJECTIVE
  To provide evidence of construct validity for the FIM instrument in the inpatient rehabilitation burn population.
  
  
  METHODS
  Confirmatory factor analysis and item response theory were used to assess construct validity. Confirmatory factor analysis was performed on a 2-factor model of the FIM instrument and on a 6-subfactor model. Mokken scale analysis, a nonparametric item response theory, was performed on each of the FIM instrument's 2 major factors, motor and cognitive domains. Internal consistency using Cronbach alpha and Molenaar and Sijtsma's statistic was also examined.
  
  
  METHODS
  Inpatient rehabilitation facilities.
  
  
  METHODS
  Data from the Uniform Data System for Medical Rehabilitation for patients with an impairment code of burn injury from the years 2002 to 2011 were used for this analysis. A total of 7569 subjects were included in the study.
  
  
  METHODS
  Not applicable.
  
  
  METHODS
  Comparative fit index results for the confirmatory factor analyses and adherence to assumptions of the Mokken scale model.
  
  
  RESULTS
  Confirmatory factor analysis provided a comparative fit index of .862 for the 2-factor model and .941 for the 6-subfactor model. Mokken scale analysis showed scalability coefficients of .681 and .891 for the motor and cognitive domains, respectively. Measures of internal consistency statistic gave values of >.95 for each major domain of the FIM instrument.
  
  
  CONCLUSIONS
  The FIM instrument has evidence of validity and reliability as an outcome measure for patients with burn injuries in the inpatient rehabilitation setting. The 6-subfactor model provides a better fit than the 2-factor model by confirmatory factor analysis. There is evidence that the motor and cognitive domains each form valid unidimensional metrics based on nonparametric item response theory.
authors.affiliation: Department of Physical Medicine and Rehabilitation, Spaulding Rehabilitation Hospital, Harvard Medical School, Boston, MA, USA. pbgerrard@partners.org
authors.forename: Paul
authors.initials: P
authors.lastname: Gerrard
authors.forename: Richard
authors.initials: R
authors.lastname: Goldstein
authors.forename: Margaret A
authors.initials: MA
authors.lastname: Divita
authors.forename: Colleen M
authors.initials: CM
authors.lastname: Ryan
authors.forename: Jacqueline
authors.initials: J
authors.lastname: Mix
authors.forename: Paulette
authors.initials: P
authors.lastname: Niewczyk
authors.forename: Lewis
authors.initials: L
authors.lastname: Kazis
authors.forename: Karen
authors.initials: K
authors.lastname: Kowalske
authors.forename: Ross
authors.initials: R
authors.lastname: Zafonte
authors.forename: Jeffrey C
authors.initials: JC
authors.lastname: Schneider
mesh_terms: D000203:Activities of Daily Living; D000328:Adult; D000368:Aged; D002056:Burns / Q000503:physiopathology / Q000523:psychology / Q000534:rehabilitation*; D003071:Cognition / Q000502:physiology; D015331:Cohort Studies; D004185:Disability Evaluation; D005163:Factor Analysis, Statistical; D005260:Female; D006760:Hospitalization; D006801:Humans; D008297:Male; D008875:Middle Aged; D009043:Motor Activity / Q000502:physiology; D017063:Outcome Assessment, Health Care; D020127:Recovery of Function / Q000502:physiology; D015203:Reproducibility of Results
keywords: Burns; CFA; Factor analysis; IIO; IRT; MSA; Mokken scale analysis; Outcome measures; Psychometrics; Rehabilitation; Validation; confirmatory factor analysis; invariant item ordering; item response theory