Association of Specific Mental Disorders With Premature Mortality in the Danish Population Using Alternative Measurement Methods.

This cohort study uses data from Danish health registers to generate estimates of years of life lost and life-years lost and to use these alternative measurement approaches to assess whether specific mental disorders are associated with premature mortality in the Danish population. Question Are specific types of mental disorders associated with premature mortality that can be quantified using alternative measurement approaches? Findings In this population-based cohort study of 6.9 million individuals with and without mental disorders in Denmark, male and female persons diagnosed with any mental disorder had life expectancies of that were 11.2 years and 7.9 years shorter, respectively, compared with the general Danish population. Drug use disorders were associated with the highest rates of excess years of life lost; however, common mental disorders, such as depressive and anxiety disorders, were also associated with substantial premature mortality. Meaning The finding that mental disorders are associated with reductions in life expectancy can provide a foundation for future intervention programs designed to reduce the differential mortality gap associated with mental disorders. Importance The association of mental disorders with premature mortality published in the Global Burden of Disease (GBD) studies has been underestimated because these analyses have recommended using only a small number of mental disorders as causes of death to estimate years of life lost (YLL). Alternative methods have been introduced, such as estimating life-years lost (LYL), to compare individuals with mental disorders with the general population. Objectives To generate register-based YLL and LYL estimates and to use these measurement methods to assess the association of specific mental disorders with premature mortality. Design, Setting, and Participants This population-based cohort study included all persons with and without mental disorders aged 0 to 94 years who were living in Denmark between January 1, 2000, and December 31, 2015. Data were analyzed from January to December 2019. Main Outcomes and Measures Danish health registers were used to identify mental disorder diagnoses, dates of death, and causes of death. The YLLs were estimated for the set of mental health-associated causes of death, and all-cause and cause-specific LYLs were estimated for 18 specific mental disorders and 3 broad categories of mental disorders that were recommended for use in the GBD studies. The association between the number of comorbid mental disorders (divided into categories of persons with >= 1 type of disorder, >= 2 types of disorders, >= 3 types of disorders, and >= 4 types of disorders) and LYL estimates was also examined. Results A total of 6989627 individuals (3481219 male persons [49.8%] and 3508408 female persons [50.2%]; mean [SD] age at study enrollment, 32.2 [24.4] years) were followed up for a total of 85911461 person-years. The YLL rates per 100000 person-years were highest for alcohol use disorder (for male individuals, 568.7 [95% CI, 564.4-572.7]; for female individuals, 155.5 [95% CI, 153.5-157.9]) and suicide (for male individuals, 590.1 [95% CI, 583.8-596.5]; for female individuals, 202.3 [95% CI, 198.5-206.4]). Although only 3 of 18 mental and substance use disorders could be associated with YLL, all mental disorders were associated with shorter life expectancies when LYL was used for measurement. Male and female individuals diagnosed with any mental disorder had life expectancies that were shorter by 11.2 years (95% CI, 11.1-11.3 years) and 7.9 years (95% CI, 7.8-8.0 years), respectively, and remaining life expectancy decreased further among those with comorbid mental disorders. Drug use disorders were associated with the highest excess LYL estimates; however, common mental disorders, such as depressive and anxiety disorders, were also associated with substantial premature mortality. Conclusions and Relevance Mental disorders were observed to be associated with reductions in life expectancy. This finding provides a foundation for future intervention programs designed to reduce the differential mortality gap associated with mental disorders. Register-based studies allow the calculation of precise individual-level YLLs and LYLs, and both measurement methods are informative for health care planning. Compared with YLL, the novel LYL measurement approach may more precisely capture the association of mental disorders with premature mortality and facilitates the exploration of comorbidity and specific causes of death in individuals with mental disorders.