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.