Individuals with intellectual disabilities experience health disparities1 and are more likely to have multiple comorbidities2 such as obesity, epilepsy, mental disorders,3 and diabetes,4 which may contribute to higher morbidity and mortality rates than the general population.5,6 They are reported to die up to 20 years earlier, with studies reporting standardized mortality rates (SMRs) ranging from 2 to 5.6 One of the leading causes of death in people with intellectual disability are circulatory diseases,5,6 among which specific diseases such as myocardial infarction (MI) or ischemic stroke may be preventable through healthcare interventions. Individuals with intellectual disability experience barriers to good quality healthcare7,8; hence identifying gaps and inequalities in health outcomes may help guide policies to improve the health status of individuals with intellectual disability.

Recent studies on mortality in individuals with intellectual disability reported 3 to 4-fold increased risk of death due to circulatory diseases compared to matched controls.5,9 Other previous studies reported less or similar risk of death due to circulatory or vascular diseases in individuals with intellectual disability compared with the general population but were limited by small sample sizes and did not take into account relevant confounders except age.7,10

Cardiovascular outcomes per se have been less studied than mortality as an outcome for individuals with intellectual disability, with inconsistent findings.3,11, 12, 13 A recent Danish study reported increased risk of CVD and stroke, and a non-significant risk for myocardial infarction (MI).12 In contrast, some studies reported that the incidence13 or the prevalence11 of MI and stroke were similar to those of the general population, while another reported higher prevalence of coronary heart disease in those without intellectual disability3 but were limited by a short follow-up period,13 cross-sectional design,3 small sample sizes,11,13 inclusion of only those over 50 years old,11,13 and no direct comparison with a control group.13

The Korean government implemented a national registration system for individuals with disabilities, including those with intellectual disability as one of the fifteen categories.14 Moreover, to the best of our knowledge no study has investigated the risk of MI and ischemic stroke in individuals with intellectual disability compared with the general population in an Asian population. CVD can be disabling and lead to long-term disease burden and reduced quality of life.15,16 While a decrease in global CVD mortality was recently reported, ischemic heart disease and stroke remained among the leading causes of age-standardized disability-adjusted life years.17 This may be attributed to increased awareness and modification of risk factors, along with timely intervention in the acute stages of CVD.18 Examining specific CVD outcomes, rather than mortality alone, may help identify diseases requiring early intervention and preventive measures to reduce morbidity due to CVD.

Therefore, we aimed to investigate the risk of CVD including MI and ischemic stroke, and death due to circulatory diseases in individuals with intellectual disability compared to the general population using a nationwide database.