Abstract
Background
The Global Burden of Disease (GBD) study uses Years of Life Lost (YLLs) to quantify premature mortality. This is a useful metric from many perspectives, however because GBD acknowledges only a small number of mental disorders as causes of death (CoDs), the true impact of mental disorders on premature mortality is underestimated. Recently, methods have been introduced that compare people with a disorder to the general population by estimating Life Years Lost (LYLs). The aim of this study was to present register-based estimates of both YLLs and LYLs related to mental disorders.
Methods
We used nationwide registers to examine a cohort of all 6,989,627 people aged 0–94 years living in Denmark in 2000–2015. Using the GBD approved set of mental health-related CoDs (eating disorders, drug use disorders, alcohol use disorder and suicide), YLLs were estimated. In addition, we calculated all-cause and cause-specific differences in life expectancy after a mental disorder diagnosis as excess LYLs between those with a specific mental disorder and the age- and sex-matched general Danish population. The disorders of interest were alcohol use disorder, drug use disorders, schizophrenia, bipolar disorders, depressive disorders, anxiety disorders, eating disorders, personality disorders, developmental intellectual disability, autism spectrum disorders, ADHD and conduct disorder. Excess LYLs related to counts of comorbid mental disorders were also examined (i.e. those diagnosed with at least two, three or four disorders).
Results
Alcohol use disorder and suicide were the leading causes of YLLs (alcohol use disorder: Men 568.7 YLLs, women 155.5 YLLs per 100,000 person-years; suicide: Men 590.1 YLLs, women 202.3 YLLs per 100,000 person-years). However, all mental disorders were associated with shorter life expectancies using LYLs. Men and women diagnosed with any mental disorder had 11.22 (95% CI 11.09; 11.35) and 7.89 (95% CI 7.76; 8.01) years shorter life expectancies respectively, and the difference increased in those with comorbid mental disorders. Drug use disorders were associated with the largest excess LYLs (17.99 (95% CI 17.49; 18.53) in men and 15.29 (95% CI 14.70; 15.88) in women), however common disorders such as depressive disorders and anxiety disorders were also associated with substantive premature mortality (e.g. in men, 8.27 and 7.52 LYLs, respectively). Schizophrenia was associated with 13.80 (95% CI 13.47; 14.14) excess LYLs in men and 11.77 (95% CI 11.38; 12.13) in women.
Discussion
Register-based studies allow the calculation of precise individual YLLs and LYLs. The novel LYL metric seems to better capture the true impact of mental disorders on premature mortality and also facilitates the exploration of comorbidity and specific CoDs in those with mental disorders.
Comparisons of insight in schizophrenia, bipolar I disorder, and depressive disorders with and without comorbid alcohol use disorder
