Aim  To examine the stability of caregiver-reported classifications of function of children with cerebral palsy (CP) measured 12 months apart.

Method  Participants were 86 children (50 males, 36 females) with CP of all motor types and severities who were recruited into a population-based longitudinal study. Children were aged 11 years 8 months (SD 6mo) on the first assessment and 12 years 8 months (SD 6mo) on the second assessment. Data were gathered through a postal survey. Caregivers reported on the Manual Ability Classification System (MACS), the Gross Motor Function Classification System (GMFCS), and other demographic characteristics. The percentage absolute agreement and the intraclass coefficient correlation (ICC) equivalent of the weighted kappa were calculated to assess consistency between assessments for the MACS and GMFCS. We also examined associations between changes in classification and background variables.

Results  Fifty-eight caregivers (67%) classified their child at the same MACS level on both assessments (ICC 0.92; 95% confidence interval [CI] 0.87–0.95), whereas 79% did so with the GMFCS (ICC 0.95; 95% CI 0.92–0.96). The evidence suggests that caregivers who were not born in Australia or who spoke a language other than English in the home were more likely to classify their child differently on the MACS at the second assessment, although this was not evident for the GMFCS.

Interpretation  Caregiver-reported MACS and GMFCS levels were generally stable over 12 months.