Parent reporting of the GMFCS: How does it compare to classifications made by clinicians?

In Brief © Chris Morris, 2007

The Gross Motor Function Classification System (GMFCS) is a widely used method for classifying the movement ability of children with cerebral palsy. Motor function is classified based on observation of a child's self-initiated movement and need for assistive technology and/or wheeled mobility (Palisano et al., 1997). There are five levels from Level I, in which a child is able to walk and run, but has some difficulty with more advanced gross motor skills, to Level V in which a child has almost no self-initiated movement ability. There are four age bands: under 2 years, 2 to 4 years, 4 to 6 years, and 6 to 12 years. Health professionals have been shown to classify children consistently in the same level most of the time; therefore, the system is said to be 'reliable' (Palisano et al., 1997; Wood & Rosenbaum, 2000). This 'In Brief' describes two studies that examined whether the GMFCS could be reliably reported by a child's parent or caregiver.

Why did we do this study?

To date, use of the GMFCS has relied upon a health professional, typically a therapist, to classify a child based on observation or through review of descriptive medical records. We felt it would be appropriate for a parent or caregiver to complete the assessment, particularly given that parents are likely to be most familiar with their child's abilities. If shown to be reliable, parent completion would have many benefits for parents, research, and community health administration.

Who participated in this study?

The study participants were the parents of children with cerebral palsy between 6 and 12 years old, and the children's health professionals. In Canada, we invited the families of 200 children who had taken part in the Ontario Motor Growth (OMG) Study. In the United Kingdom, we invited families of over 300 children identified from the 4Child database used to monitor the prevalence of cerebral palsy. Children with all sub-types and distribution of cerebral palsy were included. Although only about half of the invited families agreed to take part and returned questionnaires for each survey, we did not find any known differences between those who did and did not participate.

What was done?

In Canada, classifications using the GMFCS had been made by physical therapists as part of the OMG study. So, we carried out a survey with the parents and compared their classification to the therapists' classifications. As there was approximately a one year delay between these assessments the stability of the GMFCS over time was considered. To gather parent reported classifications, a one-page questionnaire, the GMFCS Family Report Questionnaire, was devised from the standard GMFCS user instructions. The form included five jargon-free descriptions relating to the abilities of children in the 6 to 12 years age group. Parents were asked to indicate which of the description best represented their child's movement ability. Parents in the United Kingdom completed the same survey, but were also asked to identify their child's health professionals. The nominated clinicians were then surveyed within one month to obtain their assessments using the standard instructions.

What was found?

Many parents and health professionals agreed precisely on a child's level of ability and disagreement by more than one GMFCS level was extremely rare. The agreement and reliability between parents and the clinicians was similar to that observed between health professionals (that is, between physiotherapists, orthopaedic surgeons and paediatricians). For the statistically-minded, agreement between assessments was corrected for chance-agreement using Cohen's kappa coefficient, and reliability was determined using the Intraclass Correlation Coefficient (ICC). Further details of how to interpret these statistics is provided in the publications by Morris and colleagues (2004 & 2006). In brief, the kappa statistics were around 0.5, and ICCs between parents and health professionals exceeded 0.9 representing fair to good agreement and excellent reliability.

What do the findings mean?

Parents of children ages 6 to 12 years have been shown to be reliable informants to classify their children's gross motor function. These findings have been confirmed in similar studies with children of the same and different ages, which also found high reliability between parent and health professional ratings (Dietrich et al., 2005; McDowell et al., 2007). The use of the GMFCS Family Report Questionnaire is a method that is suitable for use in research and clinical practice.

Why do people disagree on GMFCS levels and is somebody wrong?

Disagreement between individuals in classification of children's gross motor function may occur for a number of reasons. One reason is that individuals may simply interpret the rating instructions differently; and in these studies, the precise instructions given to clinicians and parents to make their classification were presented in a slightly different format. However, another factor is that individuals may have different knowledge of the child's abilities. Some children perform differently depending upon where they are (for instance in hospital, at school or in their home). As the family is likely to know how the child performs across a broader range of environments, the child may be classified at a different level by parents and health professionals.

How can the GMFCS Family Report Questionnaire be used?

In clinical practice, asking parents to classify their children using the GMFCS Family Report Questionnaire recognizes the parents' knowledge of their child's gross motor skills. This input could be enlightening for clinicians and might provide greater insight into a child's abilities than could be determined during a clinical assessment. It also provides a starting point to discuss the child's likely prognosis and to set appropriate treatment goals for therapy. Further, this method supports a family-centred approach to practice, which might strengthen partnerships between parents and health professionals.

For researchers, the GMFCS Family Report Questionnaire is an efficient way to classify children's gross motor function in large populations or when it is not feasible for a health professional to make the classification.

Copies of the GMFCS Family Report Questionnaires can be obtained on the CanChild website…

For more information, contact…

Chris Morris, Department of Public Health, University of Oxford, UK christopher.morris@dphpc.ox.ac.uk

  • Click here for list of references

    Dietrich, A., Abercrombie, K., Fanning, J.K. & Bartlett, D. (2005). Correspondence of classification of motor function of children with cerebral palsy aged two to four years between families and professionals: A pilot study. Developments, Newsletter of the Pediatric Division of the Canadian Physiotherapy Association, Spring, 10-14.

    McDowell, B.C., Kerr, C. & Parkes, J. (2007). Interobserver agreement of the Gross Motor Function Classification System in an ambulant population of children with cerebral palsy. Developmental Medicine and Child Neurology, 49, 528-533.

    Morris, C., Kurinczuk, J.J., Fitzpatrick, R. & Rosenbaum, P. (2006). Who best to make the assessment? Professionals and families' classifications of gross motor function are highly consistent. Archives of Disease in Childhood, 91, 675-679.

    Morris, C., Galuppi, B. & Rosenbaum, P. (2004) Reliability of Family Report for the Gross Motor Function Classification System. Developmental Medicine and Child Neurology, 46 (7), 455-460.

    Palisano, R., Rosenbaum, P., Walter, S., Russell, D., Wood, E. & Galuppi, B. (1997). Development and reliability of a system to classify gross motor function in children with cerebral palsy. Developmental Medicine and Child Neurology, 39, 214-223.

    Wood, E. & Rosenbaum, P. (2000). The Gross Motor Function Classification System for cerebral palsy: A study of reliability and stability over time. Developmental Medicine and Child Neurology, 42, 292-296.