title: Stability of the Gross Motor Function Classification System in children and adolescents with cerebral palsy: a retrospective cohort registry study.
abstract: To investigate the stability and to determine factors that affect change in the Gross Motor Function Classification System (GMFCS) in a sample from the total population with cerebral palsy (CP) in two regions of Sweden.
  
  
  
  Retrospective cohort registry study based on the follow-up programme for CP. Children with CP and a minimum of two GMFCS ratings were included. Subtype, sex, ages at GMFCS ratings, time between ratings, number of ratings, assessor change, and birth cohort were analysed in relation to initial GMFCS levels, with descriptive statistics and logistic regression models.
  
  
  
  Ninety-three per cent (n=736) of children with CP born between 1990 and 2007 were included, resulting in 7922 assessments between 1995 and 2014. Fifty-six per cent of the children received the same GMFCS rating at all assessments, with a median of 11 individual GMFCS ratings (range 2-21) and a median of three different assessors (range 1-10). Changes were often transient; downward change (higher performance) was more likely in GMFCS levels II and III than in the other levels. The probability of upward change (lower performance) was lowest in unilateral spastic CP.
  
  
  
  The results support the stability of the GMFCS shown previously and add new information on the properties of the classification.
authors.affiliation: Department of Clinical Sciences, Orthopedics, Lund University, Lund, Sweden.|Skåne University Hospital, Lund, Sweden.
authors.forename: Ann
authors.identifier: 0000-0001-9430-263X
authors.initials: A
authors.lastname: Alriksson-Schmidt
authors.affiliation: Department of Health Sciences, Lund University, Lund, Sweden.
authors.forename: Eva
authors.initials: E
authors.lastname: Nordmark
authors.affiliation: Epidemiology and Register Center South, Lund, Sweden.
authors.forename: Tomasz
authors.initials: T
authors.lastname: Czuba
authors.affiliation: Skåne University Hospital, Lund, Sweden.|Department of Clinical Sciences, Paediatrics, Lund University, Lund, Sweden.
authors.forename: Lena
authors.initials: L
authors.lastname: Westbom
mesh_terms: D000293:Adolescent; D002547:Cerebral Palsy / Q000145:classification* / Q000503:physiopathology; D002648:Child; D002675:Child, Preschool; D005500:Follow-Up Studies; D006801:Humans; D016015:Logistic Models; D009048:Motor Skills / Q000145:classification*; D012042:Registries; D012189:Retrospective Studies; D013548:Sweden; D013997:Time Factors