Mortality in mental disorders and global disease burden implications: a systematic review and meta-analysis

Despite the potential importance of understanding excess mortality among people with mental disorders, no comprehensive meta-analyses have been conducted quantifying mortality across mental disorders.

To conduct a systematic review and meta-analysis of mortality among people with mental disorders and examine differences in mortality risks by type of death, diagnosis, and study characteristics.

We searched EMBASE, MEDLINE, PsychINFO, and Web of Science from inception through May 7, 2014, including references of eligible articles. Our search strategy included terms for mental disorders (eg, mental disorders, serious mental illness, and severe mental illness), specific diagnoses (eg, schizophrenia, depression, anxiety, and bipolar disorder), and mortality. We also used Google Scholar to identify articles that cited eligible articles.

English-language cohort studies that reported a mortality estimate of mental disorders compared with a general population or controls from the same study setting without mental illness were included. Two reviewers independently reviewed the titles, abstracts, and articles. Of 2481 studies identified, 203 articles met the eligibility criteria and represented 29 countries in 6 continents.

One reviewer conducted a full abstraction of all data, and 2 reviewers verified accuracy.

Mortality estimates (eg, standardized mortality ratios, relative risks, hazard ratios, odds ratios, and years of potential life lost) comparing people with mental disorders and the general population or people without mental disorders. We used random-effects meta-analysis models to pool mortality ratios for all, natural, and unnatural causes of death. We also examined years of potential life lost and estimated the population attributable risk of mortality due to mental disorders.

For all-cause mortality, the pooled relative risk of mortality among those with mental disorders (from 148 studies) was 2.22 (95% CI, 2.12-2.33). Of these, 135 studies revealed that mortality was significantly higher among people with mental disorders than among the comparison population. A total of 67.3% of deaths among people with mental disorders were due to natural causes, 17.5% to unnatural causes, and the remainder to other or unknown causes. The median years of potential life lost was 10 years (n = 24 studies). We estimate that 14.3% of deaths worldwide, or approximately 8 million deaths each year, are attributable to mental disorders.

These estimates suggest that mental disorders rank among the most substantial causes of death worldwide. Efforts to quantify and address the global burden of illness need to better consider the role of mental disorders in preventable mortality.