Who best to make the assessment? Professionals' and families' classifications of gross motor function in cerebral palsy are highly consistent

Aim: To determine the reliability of family assessment for the Gross Motor Function Classification System ( GMFCS) for children with cerebral palsy in the UK. Methods: Families of a complete geographically defined population of children with cerebral palsy between 6 and 12 years old were identified from the 4Child epidemiological database. Postal surveys were conducted with the families and any of the child's health professionals that were nominated by the families. Results: Families of 129/314 eligible children took part in the study ( 41%). The indices of agreement and reliability between families and professionals were also equivalent to those observed between the professionals ( kappa = 0.5, ICC >= 0.9). Reliability coefficients were higher when more of the professionals classified children using direct observation rather than only reviewing their clinical records. Conclusions: Despite excellent reliability, families and professionals did not always agree exactly on a child's GMFCS level. Classifications may differ due to children's varying performance in different environments, in which case families will almost certainly know their children's ability in a broader range of settings. The indices of reliability of family assessment for the GMFCS meet the recommended criteria for use with individuals and groups, indicating that the method is suitable for use in research studies and clinical practice.