title: Variability explained by strength, body composition and gait impairment in activity and participation measures for children with cerebral palsy: a multicentre study.
abstract: OBJECTIVE
  To determine the amount of variability in scores on activity and participation measures used to assess ambulatory individuals with cerebral palsy explained by strength, body composition, gait impairment and participant characteristics.
  
  
  METHODS
  Multicentre prospective cross-sectional study.
  
  
  METHODS
  Seven paediatric-orthopaedic specialty hospitals.
  
  
  METHODS
  Three hundred and seventy-seven ambulatory individuals (241 males, 136 females) with cerebral palsy, Gross Motor Function Classification System (GMFCS) levels I-III (I = 148, II = 153, III = 76), ages 8-18 years (mean 12 years 9 months, SD 2 years 8 months).
  
  
  METHODS
  Participants completed assessments of GMFCS level, patient history, lower extremity muscle strength, Gross Motor Function Measure (GMFM-66), Pediatric Outcomes Data Collection Instrument (PODCI), instrumented gait analysis, 1 minute walk test, Timed Up-and-Go and body composition. Multiple linear regression and bootstrap analyses were performed for each outcome measure, stratified by GMFCS level.
  
  
  RESULTS
  The amount of variability in outcome measures explained by participant characteristics, strength, and gait impairment ranged from 11% to 50%. Gait impairment was the most common predictor variable and frequently explained the greatest variance across all outcome measures and GMFCS levels. As gait impairment increased, scores on outcome measures decreased. Strength findings were inconsistent and not a primary factor. Body composition contributed minimally (<4%) in explaining variability. Participant characteristics (cerebral palsy type, gestational age and age at walking onset), were significant predictor variables in several models.
  
  
  CONCLUSIONS
  Variability in outcome measure scores is multifaceted and only partially explained by strength and gait impairment illustrating the challenges of attempting to explain variation within this heterogeneous population. Clinicians treating individuals with cerebral palsy should consider this when developing treatment paradigms.
authors.affiliation: Shriners Hospital for Children, Lexington, KY, USA doeffinger@shrinenet.org.
authors.forename: Donna
authors.initials: D
authors.lastname: Oeffinger
authors.affiliation: Clinical Outcome Assessment Laboratory, Shriners Hospital for Children, Springfield, MA, USA.
authors.forename: George
authors.initials: G
authors.lastname: Gorton
authors.affiliation: Shriners Hospital for Children, Chicago, IL, USA.
authors.forename: Sahar
authors.initials: S
authors.lastname: Hassani
authors.affiliation: Motion Analysis Laboratory, Shriners Hospital for Children, Northern California, USA.
authors.forename: Mitell
authors.initials: M
authors.lastname: Sison-Williamson
authors.affiliation: Shriners Hospital for Children, Salt Lake City, UT, USA.
authors.forename: Barbara
authors.initials: B
authors.lastname: Johnson
authors.affiliation: Shriners Hospital for Children, Lexington, KY, USA.
authors.forename: Megan
authors.initials: M
authors.lastname: Whitmer
authors.affiliation: Department of Orthopaedics, University of Virginia, USA.
authors.forename: Mark
authors.initials: M
authors.lastname: Romness
authors.affiliation: Department of Biostatistics, University of Kentucky, USA.
authors.forename: Dick
authors.initials: D
authors.lastname: Kryscio
authors.affiliation: Shriners Hospital for Children, Lexington, KY, USA.
authors.forename: Chester
authors.initials: C
authors.lastname: Tylkowski
authors.affiliation: Motion Analysis Laboratory, Shriners Hospital for Children, Northern California, USA.
authors.forename: Anita
authors.initials: A
authors.lastname: Bagley
mesh_terms: D000293:Adolescent; D001823:Body Composition / Q000502:physiology*; D002547:Cerebral Palsy / Q000145:classification / Q000150:complications / Q000503:physiopathology*; D002648:Child; D003430:Cross-Sectional Studies; D004185:Disability Evaluation; D005260:Female; D020233:Gait Disorders, Neurologic / Q000145:classification / Q000209:etiology / Q000503:physiopathology*; D006801:Humans; D008297:Male; D009043:Motor Activity; D019957:Motor Skills Disorders / Q000145:classification / Q000209:etiology / Q000503:physiopathology*; D053580:Muscle Strength / Q000502:physiology*; D011446:Prospective Studies; D012044:Regression Analysis; D012720:Severity of Illness Index
keywords: Cerebral palsy; Gillette Gait Index; body composition; gait; outcome measures; strength