Background: Depression is a common psychiatric disorder, with a lifetime prevalence of 10-15% in the Danish population. Although depression is associated with excess mortality, it is not yet understood how this affects life expectancy. Our aim was to examine mortality rates and life expectancy in patients with unipolar depression compared to the general population, and to assess the impact of comorbid somatic illness and substance abuse.
Methods: We followed a Danish population-based cohort from 1995-2013 (N=5,103,699). The cohort included all residents in Denmark during the study period. Mortality rate ratios (MRRs) and life expectancy in persons with unipolar depression were calculated using survival analysis techniques.
Results: The overall MRR was 2.07 (95% Confidence Interval (CI): 2.05-2.09) in people with a previous unipolar depression diagnosis compared to the general Danish population. This excess mortality translated into a reduced life expectancy of 14.0 years in men and 10.1 years in women (assuming onset at age 15). The MRR was highest for death due to suicide and accidents (MRR: 4.66; 95% CI: 4.53-4.79), but the absolute number of deaths was highest for natural causes.
Conclusion: People with unipolar depression have a significant shorter life expectancy, especially men.
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