Cohort profile: Scotland's record-linkage e-cohorts of people with intellectual disabilities, and autistic people (SCIDA).

Scottish researchers created large databases linking government records to study health differences between autistic people, people with intellectual disabilities, and the general population. They found concerning health gaps: only 15% of people with intellectual disabilities and 38% of autistic people reported very good health, compared to 52% of the general population. Mental health conditions were also much more common in both disability groups. This research will help identify why these health differences exist and how to address them.

This cohort profile describes Scotland's record-linkage e-cohorts (SCIDA) established using 2011 Census data to investigate health inequalities among people with intellectual disabilities and autistic people. The cohorts include 22,538 people with intellectual disabilities and 27,741 autistic people, with representative general population samples for comparison. Successful data linkage (>92%) connected census demographics with comprehensive health records including deaths, cancer registrations, prescriptions, hospital admissions, and screening programs. Initial findings reveal significant health disparities: only 15% of people with intellectual disabilities and 38% of autistic people reported very good general health compared to 52.4% in the general population.

Mental health conditions were substantially more prevalent in both groups (21.1% and 14.4% respectively) versus 4.2% in the general population.

The substantial health disparities identified underscore the urgent need for targeted healthcare strategies for autistic people and those with intellectual disabilities. The comprehensive linked dataset will enable future research to identify specific areas for intervention, inform NDIS planning, and guide policy development to address healthcare inequalities in these vulnerable populations.

This is a cohort profile paper describing methodology rather than presenting analytical results. Findings are limited to basic demographic and health status comparisons from census data. Detailed health outcomes, mortality patterns, and causal relationships will require future analyses of the linked datasets.

To investigate health, mortality and healthcare inequalities experienced by people with intellectual disabilities, and autistic people, and their determinants; an important step towards identifying and implementing solutions to reduce inequalities. This paper describes the cohorts, record-linkages and variables that will be used. Scotland's Census, 2011 was used to identify Scotland's citizens with intellectual disabilities, and autistic citizens, and representative general population samples with neither. Using Scotland's community health index, the Census data (demography, household, employment, long-term conditions) were linked with routinely collected health, death and healthcare data: Scotland's register of deaths, Scottish morbidity data 06 (SMR06: cancer incidence, mortality, treatments), Prescribing Information System (identifying asthma/chronic obstructive pulmonary disease; angina/congestive heart failure/hypertension; peptic ulcer/reflux; constipation; diabetes; thyroid disorder; depression; bipolar disorders; anxiety/sleep; psychosis; attention deficit hyperactivity disorder; epilepsy; glaucoma), SMR01 (general/acute hospital admissions and causes, ambulatory care sensitive admissions), SMR04 (mental health admissions and causes), Scottish Care Information-Diabetes Collaboration (diabetic care quality, diabetic outcomes), national bowel screening programme and cervical screening.

Of the whole population, 0.5% had intellectual disabilities, and 0.6% were autistic. Linkage was successful for >92%. The resultant e-cohorts include: (1) 22 538 people with intellectual disabilities (12 837 men and 9701 women), 4509 of whom are children <16 years, (2) 27 741 autistic people (21 390 men and 6351 women), 15 387 of whom are children <16 years and (3) representative general population samples with neither condition. Very good general health was reported for only 3389 (15.0%) people with intellectual disabilities, 10 510 (38.0%) autistic people, compared with 52.4% general population.

Mental health conditions were reported for 4755 (21.1%) people with intellectual disabilities, 3998 (14.4%) autistic people, compared with 4.2% general population. Analyses will determine the extent of premature mortality, causes of death, and avoidable deaths, profile of health conditions and cancers, healthcare quality and screening and determinants of mortality and healthcare.