Cohort profile: understanding health service system needs for people with intellectual disability using linked data in New South Wales, Australia

This cohort profile describes one of the largest linked datasets in the world concerning the health of people with intellectual disability. The cohort comprises a retrospective group of 100,089 individuals with intellectual disability who received disability and/or health services in New South Wales, Australia. Of these participants, 34% were female, with a median age at cohort entry of 3 years (interquartile range, 0-19). A separate comparator cohort included 455,677 individuals, matched by 5-year age group, sex, and residential postcode at a 5:1 ratio. Initial results indicate that between 2001 and 2018, people with intellectual disability experienced more than double the rate of hospitalisations (538 vs. 235 per 1,000 person-years), as well as markedly higher rates of emergency department presentations (707 vs. 379 per 1,000 person-years) and use of ambulatory mental health services (1,012 vs. 157 per 1,000 person-years), relative to the comparator cohort. The largest disparities in hospital admissions were for mental disorders, dialysis, and diseases of the nervous system and sense organs. Furthermore, individuals with intellectual disability had more than double the rate of dispensed medications found in the comparator cohort. Of these medications, 46.6% were for the treatment of nervous system conditions, as opposed to 24.7% for the comparator cohort. The mean +/- standard deviation age at death was 52 +/- 19 years for people with intellectual disability and 64 +/- 22 years for the comparator participants.