Analysis Tells Story of Global Burden of Mental Illness–Related Mortality

Mental disorders rank among the most common causes of death worldwide, according to a meta-analysis published online February 11 in JAMA Psychiatry.

An estimated 14.3 percent of deaths worldwide, or approximately 8 million deaths each year, are attributable to mental disorders, according to the new report. The authors were Elizabeth Reisinger Walker, Ph.D., M.P.H., Robin McGee, M.P.H., and Benjamin Druss, M.D., of Emory University.

They searched Embase, Medline, PsycINFO, and Web of Science from inception through May 7, 2014, including references of eligible articles, using the following search terms for mental disorders, specific diagnoses, and mortality: mental disorders, serious mental illness, severe mental illness, schizophrenia, depression, anxiety, and bipolar disorder.

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. Of 2,481 studies identified, 203 articles met the eligibility criteria and represented 29 countries on six continents.

The variable of interest was mortality estimates (standardized mortality ratios, relative risks, hazard ratios, odds ratios, and years of potential life lost) for people with mental disorders and the general population or subpopulations of people without mental disorders. The researchers used statistical analysis models to pool mortality ratios for all, natural, and unnatural causes of death; they also examined years of potential life lost and estimated the population 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—indicating that people with mental illness had slightly more than twice the risk of dying prematurely than comparison groups of people without mental illness. Of these studies, 135 revealed that mortality was significantly higher during study periods among people with mental disorders than among the comparison population. Fourteen studies reported no significant difference in mortality risks between the two groups, and no studies reported lower mortality risks for people with mental disorders.

Analysis showed that 67.3 percent of deaths among people with mental disorders were due to natural causes, 17.5 percent to unnatural causes, and the remainder to unknown causes.

Twenty-four studies included estimates of years of potential life lost (YPLL) for people with mental disorders. Results from all these studies indicated that people with mental disorders had more YPLL compared with people in the general population. For all-cause mortality, the reduction in life expectancy ranged from 1.4 to 32 years, with a median of 10.1 years.

Interestingly, length of follow-up was associated with differential risks of mortality; studies with longer follow-up tended to report lower mortality ratios compared with studies with a follow-up of 10 or fewer years.

“One explanation is that people with mental illness [may] die earlier and that, during a long follow-up, the background rate of mortality among people without mental illness starts to catch up with people with mental illness as the whole sample ages,” the researchers suggested.

Druss has been a leader in the movement toward integrated care and a focus on population health, and he has emphasized the critical importance of improving care for chronic general medical conditions of people with mental illness in public systems (Psychiatric News, October 4, 2013).

He and colleagues said the mortality statistics argue for the importance of collaborative care. “Prevention aimed at reducing mental disorders and chronic medical conditions is crucial,” they wrote. “Prevention and care of chronic medical conditions among people with mental disorders require promotion of healthy behaviors, early diagnosis and coordinated management, and integrated care between the mental health and medical systems. People with mental disorders often do not receive preventive services, such as immunizations, cancer screenings, and tobacco counseling and often receive a lower quality of care for medical conditions.” ■