Effects of Chronic Diseases on All-Cause Mortality in People with Mental Illness: A Retrospective Cohort Study Using the Korean National Health Insurance Service-Health Screening

The aim of this study was to compare mortality and the prevalence of chronic diseases between people with mental illness and the general population, and to explore which chronic diseases increase the risk of all-cause mortality, especially in people with mental illness. This study assessed data from the 2002–2019 Korean National Health Insurance Service-Health Screening sample cohort. Results revealed that all-cause mortality was higher in people with mental illness compared to people without mental illness (11.40% vs. 10.28%, p = 0.0022). Several chronic diseases have a higher prevalence and risk of all-cause mortality in individuals with mental illness than the general population. Among people with the same chronic disease, those with mental disorders had a higher risk of all-cause mortality. Cancer (aHR 2.55, 95% CI 2.488–2.614), liver cirrhosis (aHR 2.198, 95% CI 2.086–2.316), and arrhythmia (aHR 1.427, 95% CI 1.383–1.472) were the top three chronic diseases that increased the risk of all-cause mortality in people with mental illness compared to people without mental illness. Our results suggest the need for more attention to chronic diseases for people with mental illness in clinical practice by explaining the effect of chronic disease on all-cause mortality in people with mental illness.