Physical and mental health during transition to adulthood in young people with and without intellectual disabilities: Analysis of a whole population of 815,889 young people in Scotland

Background
Transition to adulthood may be a period of vulnerability for health for individuals with intellectual disabilities. No large-scale studies have compared the health of individuals with and without intellectual disabilities undergoing transition. The aims of this study were (1) to compare health during transition for individuals with and without intellectual disabilities across a whole country population and (2) to establish whether transition is associated with health in the population with intellectual disabilities.

Methods
Data were drawn from Scotland's Census, 2011. Frequency data were calculated for young people with and without intellectual disabilities. Logistic regressions were used to determine the extent to which intellectual disabilities account for seven health outcomes (general health, mental health, physical disabilities, hearing impairment, visual impairment, long-term illness and day-to-day activity limitations), adjusted for age and gender. Within the intellectual disabilities population, logistic regressions were then used to determine whether age group (13–18 or 19–24 years) is associated with the seven health outcomes, adjusted by gender.

Results
A total of 5556/815 889 young people aged 13–24 years had intellectual disabilities. Those with intellectual disabilities were 9.6–125.0 times more likely to have poor health on the seven outcomes. Within the population with intellectual disabilities, the 19- to 24-year-olds with intellectual disabilities were more likely to have mental health problems than the 13- to 18-year-olds, but did not have poorer health on the other outcomes. The difference between age groups for mental health problems was greater for young people who did not have intellectual disabilities, but their overall level of mental health problems was substantially lower than for the young people with intellectual disabilities.

Conclusions
This largest-to-date study quantifies the extent of the substantial health disparities experienced by young people with intellectual disabilities compared with people without intellectual disabilities. The young population with intellectual disabilities have substantial health problems; therefore, transition between child and adult services must be carefully planned in order to ensure that existing health conditions are managed and emerging problems minimised.