The stability of the Manual Ability Classification System over time

AimTo evaluate the stability over time of the Manual Ability Classification System (MACS) levels. MethodThe study group comprised 1267 children with cerebral palsy (746 males, 521 females) who were followed from 2005 to 2010 with two or more registered MACS classifications rated at least 1year apart. Thirty-five percent of the children (n=445) had four MACS registrations. The children were between 4 and 17years old at their first rating, The stability over time was also compared between children who were younger (4y of age) or older (10y) at the time of their first classification. ResultsAn excellent stability was found between two ratings at 1-year intervals with an intraclass correlation coefficient (ICC) of 0.97 (95% CI 0.97-0.97) and 82% agreement (n=1267). The stability was also excellent for two ratings performed 3 to 5years apart (ICC 0.96; 95% CI 0.95-0.97) with an agreement of 78% (n=445). Across four ratings, 70% of the children remained at the same level. The results were similar for younger and older children, indicating that stability was not influenced by age. InterpretationThis study provides evidence that MACS levels are stable over time and that the classification has predictive value.