Background: While a number of studies have examined the development of skills in children with intellectual disabilities (ID), most have been cross-sectional, most have been concerned with particular syndromes such as Down's syndrome or autism and few have attempted to identify factors associated with improvements in skills.
Methods: From a sample of 111 children with severe ID who had been identified from the registers of six special schools at 4-11 years of age, 82 were traced and reassessed 5 years later at the age of 11-17 years. On both occasions, information on the children's handicaps and skills was collected by interviewing their main carers using a shortened version of the Vineland Adaptive Behaviour Scales and the Disability Assessment Schedule.
Results and conclusions: There were small but statistically significant improvements in Vineland age-equivalent communication and daily living skills scores, but not in Vineland Socialization scores, over the 5-year period of follow-up. This pattern of improvement was observed in most aetiological subgroups. Improvement in skills was greatest in younger children, and was associated with reductions in behaviour problems and in levels of parental stress. In spite of the improvements in age-equivalent scores, Vineland standard scores showed significant declines over the same period of time, indicating that the improvements observed were smaller than would be expected in a general population sample of children of the same age. The dangers of using standard scores or quotients to quantify the level of functioning of children with severe ID are highlighted.