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The Gross Motor Function Classification System: 20 years on

Since its development and publication in 1997, the Gross Motor Function Classification System (GMFCS) has had significant global impact. Rarely does one read a scientific article on cerebral palsy (CP) without a reference to this important tool. It is widely used internationally and is now available in 22 languages. The GMFCS helps to educate patients, families, and health professionals regarding gross motor prognosis. This knowledge enables realistic goal setting in clinical work. In research, the GMFCS aids in population selection, description, and stratification, as well as assessment of outcome. Now, 20 years later, one may ask: does this tool still answer the clinical questions that led to its development? Is it still reliably stable? Can a multitude of health professionals learn and apply this tool for meaningful use in large databases? Such databases are required to answer important clinical research questions regarding etiology, treatment, and outcomes over the lifespan. Finally, has the introduction of the new expanded and revised version (GMFCS – E&R) changed its utility? The paper by Alriksson-Schmidt et al. provides important reassurance that this tool is still highly applicable. Despite the passage of time and evolution of the GMFCS to the GMFCS – E&R, Alriksson-Schmidt et al. provide strong evidence that the GMFCS continues to answer clinically relevant questions regarding gross motor function. The data collected here demonstrates remarkable stability from initial to final assessment even when there are a number of years between assessments, and multiple care providers scoring each patient and thousands of assessments for a given population. As well, thanks to Alriksson-Schmidt et al., we now have an up-to-date analysis of a large total population sample defined by geographical area. When using any tool, however, it is also important to be aware of trends, tendencies, and potential limitations. This is particularly important when the tool is utilized over a long period, by a large number of care providers. Despite the evidence for GMFCS stability provided by AlrikssonSchmidt et al., children and youth assessed at GMFCS levels II and III had a greater propensity for change in level, while children with unilateral spastic CP had the lowest proportion of change. Year of birth and increase in time between assessments are identified as factors related to upwards change (i.e. decreased function), while change in assessor is related to downward change (i.e. increased function). We are entering an exciting era of new advancements in the understanding and treatment of CP. There are strong databases, rapid expansion of genetic knowledge, advancement in technology for gait training, and potential new cellular treatments. As we face this time of great hope and rapid change, it is even more important to have clear, easy-to-use tools with predictable performance that have stood the test of time. With advancement in prevention strategies and treatments, there will be increasing need for careful assessment of change in function. The article by Alriksson-Schmidt et al. adds to our understanding and the strength of a brilliantly developed tool, the GMFCS.