Stability of the gross motor function classification system in children with cerebral palsy in the two to four year age band.

PURPOSE: This study aimed to investigate the stability of the Gross Motor Function Classification System (GMFCS) in children with cerebral palsy (CP) in the two to four year age band, the frequency at which children were reclassified, and trends of reclassification to higher or lower ability.

METHODS: This retrospective study included 164 children with CP between 24 to 48 months old with two or more GMFCS ratings at least 12 months apart between their second and fourth birthdays. GMFCS ratings were captured closest to 24, 36, and 48 months. Stability and reclassification trends were analyzed using inferential statistics. Frequency of reclassification, age at ratings, duration between ratings, and corresponding change rate were analyzed using descriptive statics.

RESULTS: When comparing ratings closest to second and fourth birthdays, a linear weighted kappa of 0.726 was found. Of the total population, 46.95% changed GMFCS levels at any time between two to four years of age, the majority of which were reclassified to a higher level of ability.

CONCLUSION: Findings suggest the GMFCS is less stable in the two to four year age band compared to older age bands. Due to the importance of providing accurate guidance for caregivers and high rate of reclassification, it is recommended GMFCS levels be reassessed every six months during this period of time.