The quality of life of individuals with intellectual disability: Differences between Denmark and Japan

Association of intellectual disability with overall and type-specific cardiovascular diseases: a population-based cohort study in Denmark

BACKGROUND

Individuals with mental health problems have been shown to have an increased risk of cardiovascular disorder (CVD), but little is known about the risk of early-onset CVD among those with intellectual disability. We aimed to investigate the association between intellectual disability and subsequent CVD, taking into consideration the severity of intellectual disability and neurodevelopmental and neurologic comorbidity.

METHODS

This population-based cohort study used individual-level linked data from Danish national health registries. Participants were all live-born singletons born in Denmark during 1978-2016 (n = 2,288,393). Follow-up began from birth and continued until the onset of CVD, death, emigration, or December 31, 2018, whichever came first. Clinical diagnosis of any CVD or type-specific CVDs was identified in the Danish National Patient Register. Time-varying Cox regression analyses were used to estimate the hazard ratio (HR) of intellectual disability associated with overall and type-specific CVDs.

RESULTS

A total of 11,954 individuals received a diagnosis of intellectual disability (7434 males and 4520 females). During a median follow-up time of 18.5 years (interquartile range, 18.1 years), 652 individuals with intellectual disability (5.5%) received a diagnosis of CVD (incidence rate, 2.4 per 1000 person-years), compared with 78,088 (3.4%) CVD cases in individuals without intellectual disability (incidence rate, 1.9 per 1000 person-years), corresponding to a HR of 1.24 (95% CI, 1.15-1.34). Increased risks of CVD were similar in both childhood (HR, 1.24; 95% CI, 1.08-1.43) and early adulthood (HR, 1.25; 95% CI, 1.14-1.38). For type-specific CVDs, intellectual disability was significantly associated with cerebrovascular disease (HR, 2.50; 95% CI, 2.02-3.10), stroke (HR, 2.20; 95% CI, 1.69-2.86), heart failure (HR, 3.56; 95% CI, 2.37-5.35), hypertensive disease (HR, 1.30; 95% CI, 1.22-1.39), and deep vein thrombosis (HR, 2.10; 95% CI, 1.60-2.75). Stratified HRs of overall CVD were 1.14 (95% CI, 1.01-1.30) for borderline/mild intellectual disability, 1.25 (95% CI, 1.01-1.54) for moderate intellectual disability, and 1.91 (95% CI, 1.47-2.48) for severe/profound intellectual disability. After the exclusion of individuals with neurodevelopmental and neurologic comorbidity, intellectual disability remained significantly associated with increased risks of CVD.

CONCLUSIONS

Individuals with intellectual disability had increased risks of early-onset CVD, in particular, for cerebrovascular disease, stroke, heart failure, and deep vein thrombosis, and the risks also increased with the severity of intellectual disability. Our findings highlight the awareness of increased risks of CVD in intellectual disability patients.