title: Validity and reliability of two abbreviated versions of the Gross Motor Function Measure.
abstract: BACKGROUND
  The "gold standard" for measuring gross motor function in children with cerebral palsy is the 66-item Gross Motor Function Measure (GMFM-66).
  
  
  OBJECTIVE
  The purpose of this study was to estimate the validity and reliability of 2 abbreviated versions of the GMFM-66; one version involves an item set approach, and the other version involves a basal and ceiling approach.
  
  
  METHODS
  This was a measurement study comprising concurrent validity, comparability, and test-retest reliability components.
  
  
  METHODS
  The study participants were 26 children who were 2 to 6 years of age and had cerebral palsy across all Gross Motor Function Classification System levels. In the first session, both abbreviated versions were administered by 2 independent raters; next, the full GMFM-66 was administered. In the second session, only the abbreviated versions were administered by the same raters. Concurrent validity, comparability of versions, and test-retest reliability were determined with intraclass correlation coefficients [ICC (2,1)].
  
  
  RESULTS
  Both versions demonstrated high levels of validity, with an ICC of .99 (95% confidence interval=0.972-0.997), reflecting associations with the GMFM-66. Both versions also were shown to be highly reliable, with ICCs of greater than .98 (95% confidence interval=0.965-0.994).
  
  
  CONCLUSIONS
  A smaller-than-expected sample was recruited for this study and may be a potential limitation of the study.
  
  
  CONCLUSIONS
  Both versions of the GMFM-66 can be used in clinical practice or research. However, the GMFM-66 with the basal and ceiling approach is recommended as the preferred abbreviated version.
authors.affiliation: Faculty of Health Sciences, The University of Western Ontario, 1011c Elborn College, 1201 Western Rd, London, Ontario, Canada. brunton.laura@gmail.com
authors.forename: Laura K
authors.initials: LK
authors.lastname: Brunton
authors.forename: Doreen J
authors.initials: DJ
authors.lastname: Bartlett
mesh_terms: D002547:Cerebral Palsy / Q000503:physiopathology* / Q000534:rehabilitation; D002648:Child; D002675:Child, Preschool; D005260:Female; D006305:Health Status Indicators; D006801:Humans; D007223:Infant; D008297:Male; D011594:Psychometrics; D015203:Reproducibility of Results