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Interobserver agreement of the Gross Motor Function Classification System in an ambulant population of children with
Brona C McDowell1, Claire Kerr, Jackie Parkes
1Gait Analysis Laboratory, Musgrave Park Hospital, Stockman's Lane, Belfast, UK. brona.mcdowell@belfasttrust.hscni.net
Insights
Parent and therapist agreement on Gross Motor Function Classification System (GMFCS) levels in children with cerebral palsy (CP) is good, especially with experienced therapists. Computed GMFCS levels also show substantial agreement, suggesting registry data potential.
Area of Science:
- Pediatrics
- Neurology
- Rehabilitation Medicine
Background:
- The Gross Motor Function Classification System (GMFCS) is crucial for classifying motor function in children with cerebral palsy (CP).
- Accurate GMFCS level assignment is vital for effective intervention planning and research.
- Inter-rater reliability of GMFCS assessments can vary depending on assessor experience and data source.
Purpose of the Study:
- To evaluate the agreement between different assessors (parent/guardian, research physiotherapist, community physiotherapist) and a computed GMFCS level in children with CP.
- To identify factors influencing GMFCS classification agreement, such as therapist experience and child's age.
Main Methods:
- GMFCS levels were assessed by three independent groups: parent/guardian, research physiotherapist, and community physiotherapist, for 184 children (aged 4-18 years) with CP.
- A software algorithm computed GMFCS levels from a regional CP registry data.
- Agreement was quantified using the kappa statistic with linear weighting (kappa(1w)).
Main Results:
- Good agreement was found between parent/guardian and research physiotherapist (kappa(1w)=0.75).
- Moderate agreement was observed between community physiotherapist and researcher (kappa(1w)=0.64), and community physiotherapist and parent/guardian (kappa(1w)=0.57).
- Agreement improved with increasing therapist experience and child's age; substantial agreement (kappa(1w)=0.74) was noted between computed and experienced therapist GMFCS levels.
Conclusions:
- Parental reports demonstrate good agreement with experienced research physiotherapists for GMFCS classification.
- Therapist experience and familiarity with the child enhance GMFCS grading accuracy.
- Computed GMFCS levels from CP registries hold potential for reliable classification if sufficient locomotor data is available.
Abstract:
Gross Motor Function Classification System (GMFCS) level was reported by three independent assessors in a population of children with cerebral palsy (CP) aged between 4 and 18 years (n=184; 112 males, 72 females; mean age 10y 10mo [SD 3y 7mo]). A software algorithm also provided a computed GMFCS level from a regional CP registry. Participants had clinical diagnoses of unilateral (n=94) and bilateral (n=84) spastic CP, ataxia (n=4), dyskinesia (n=1), and hypotonia (n=1), and could walk independently with or without the use of an aid (GMFCS Levels I-IV). Research physiotherapist (n=184) and parent/guardian data (n=178) were collected in a research environment. Data from the child's community physiotherapist (n=143) were obtained by postal questionnaire. Results, using the kappa statistic with linear weighting (kappa(1w)), showed good agreement between the parent/guardian and research physiotherapist (kappa(1w)=0.75) with more moderate levels of agreement between the clinical physiotherapist and researcher (kappa(1w)=0.64) and the clinical physiotherapist and parent/guardian (kappa(1w)=0.57). Agreement was consistently better for older children (>2y). This study has shown that agreement with parent report increases with therapists'experience of the GMFCS and knowledge of the child at the time of grading. Substantial agreement between a computed GMFCS and an experienced therapist (kappa(1w)=0.74) also demonstrates the potential for extrapolation of GMFCS rating from an existing CP registry, providing the latter has sufficient data on locomotor ability.
