Time Trends in the Mortality Gap for Individuals With Mental Disorders in Denmark: A Population-Based Cohort Study Over 2010-2023

BACKGROUND: The mortality gap between people with mental disorders and the general population is well established. This study aims to comprehensively investigate how mortality rates for people with mental disorders and their mortality gap have changed over time.

METHODS: We conducted a population-based cohort study using nationwide administrative data, including all people aged 1-99 years living in Denmark at some point between 2010 and 2023. Mental disorders were identified in the Danish hospital registers and classified into 10 groups. Information on mortality was obtained from population registers, and causes of death were categorized into 11 groups within the broad categories of natural causes and external causes. For each specific mental disorder, we estimated mortality rates for those diagnosed and for the general population via direct standardization using the distribution of sex and age (5-year age categories) of those diagnosed. All analyses were performed for five calendar periods (2010-2012, 2013-2015, 2016-2018, 2019-2021, and 2022-2023).

RESULTS: A total of 7,133,833 individuals were followed up for 78.0 million person-years. The mortality rate for 2010-2023 for individuals with mental disorders was 19.8 deaths (95% CI: 19.8-19.9) per 1000 person-years, while the standardized mortality ratio (SMR) was 2.15 (2.14-2.16). Mortality rates decreased for both the general population and those with mental disorders over time, while SMRs decreased from 2.47 (2.44-2.50) in 2010-2012 to 2.32 (2.28-2.36) in 2022-2023. However, these improvements were only observed in males, and only for some disorders (including depression and anxiety), and not for others (including schizophrenia or substance use disorders).

DISCUSSION: Despite improvements in the mortality rates of people with mental disorders, these have not been sufficient to close the mortality gap with the general population, especially for the most severe disorders. More initiatives are needed and existing initiatives need to be strengthened.