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Burden of Depressive Disorders

Reviewer and Curator: Larry H Bernstein, MD, FCAP

This article is an important contribution to the literature on depression, substantiation the cardiovascular burden of depression on cardiovascular disease.

Burden of Depressive Disorders by Country, Sex, Age, and Year:Findings from the Global Burden of Disease Study 2010

1Universityof Queensland, School of Population Health,Herston, Queensland, Au
2Queensland Centre for Mental Health Research, Wacol, Queensland, Au
3University of Queensland, Queensland Children’s Medical Research Institute,Herston,Queensland, Au
4Universityof Calgary, Department of Community Health Sciences,Calgary, Alberta, Ca
5University of Washington,Institute for Health Metrics and Evaluation, Seattle, Wash

Abstract

Background

Depressive disorders were a leading cause of burden in the Global Burden of Disease (GBD) 1990 and 2000  studies. Here, we analyze the burden of depressive disorders in GBD 2010 and present severity proportions ,burden by country, region, age, sex, and year, as well as burden of depressive disorders as a risk factor fo rsuicide and ischemic heart disease.

Methods and Findings

Burden was calculated for major depressive disorder (MDD) and dysthymia. A systematic review of  epidemiological data was conducted. The data were pooled using a Bayesian meta-regression. Disability weights from population survey data

• quantified the severity of health loss from depressive disorders.

These weights were used to calculate

• years lived with disability (YLDs) and
• disability adjusted life-years (DALYs).

Separate DALYs were estimated for

• suicide and
• ischemic heart disease

attributable to depressive disorders. Depressive disorders were the second leading cause of YLDs in 2010.

• MDD accounted for 8.2% (5.9%–10.8%) of global YLDs and
• dysthymia for 1.4% (0.9%–2.0%).

Depressive disorders were a leading cause of DALYs even though no mortality was attributed to them as the underlying cause.

• MDD accounted for 2.5% (1.9%–3.2%) of global DALYs and
• dysthymia for 0.5% (0.3%–0.6%).

There was more regional variation in burden for MDD than for dysthymia; with

• higher estimates in females, and
• adults of working age.

Whilst burden increased by 37.5% between 1990 and 2010, this was due to population growth and ageing. MDD explained

• 16 million  suicide DALYs and
• almost 4 million ischemic heart disease DALYs.

This attributable burden would increase the overall burden of depressive disorders from 3.0% (2.2%–3.8%) to 3.8% (3.0%–4.7%) of global DALYs.

Conclusions

GBD 2010 identified depressive disorders as a leading cause of burden. MDD was also a contributor of burden

• allocated to suicide and ischemic heart disease.

These findings emphasize the importance of including depressive disorders as a public-health priority and

• implementing cost-effective interventions to reduce its burden.

Please see later in the article for the Editors’ Summary.

Citation:Ferrari AJ, Charlson FJ, Norman RE, Patten SB, Freedman G,etal.(2013) Burden of Depressive Disorders by Country, Sex, Age, and Year: Findings from the Global Burden of Disease Study 2010. PLoS Med 10(11):e1001547. http://dx.doi.org/10.1371/journal.pmed.1001547

Abbreviations: CRA, comparative risk assessment; DALY, disability adjusted life years; DSM, Diagnostic and Statistical Manual of Mental Disorders; GBD, global burden of disease; ICD, International Classification of Diseases; MDD, major depressive disorder; MEPS, US Medical Expenditure Panel Survey; NESARC, US National Epidemiological Survey on Alcohol and Related Conditions 2000–2001 and 2004–2005; NSMHWB, Australian National Survey of Mental Health and Well being of Adults 1997; RR, relative risk; YLD, years lived with disability;YLL,years of life lost.

Figure1.YLDs by age and sex for MDD and dysthymia in 1990 and 2010.  http://dx.doi.org/10.1371/journal.pmed.1001547.g001

Figure2.YLD rates (per100,000) by region for MDD and dysthymia in 1990 and 2010. 95%UI, 95% uncertainty interval; AP-HI, Asia Pacific, high income; As-C, Asia Central; AS-E, Asia East; AS-S, Asia South;A-SE, Asia Southeast; Aus, Australasia; Caribb, Caribbean; Eur-C, Europe Central; Eur-E, Europe Eastern; Eur-W, Europe Western; LA-An, LatinAmerica, Andean; LA-C, Latin America, Central; LA-Sth, LatinAmerica, Southern; LA-Trop, Latin America, Tropical; Nafr-ME, NorthAfrica/MiddleEast; Nam-HI, North America, high income; Oc, Oceania; SSA-C, Sub-Saharan Africa, Central; SSA-E, Sub-Saharan Africa, East; SSA-S, Sub-Saharan Africa Southern; SSA-W, Sub-Saharan Africa,West.  http://dx.doi.org/10.1371/journal.pmed.1001547.g002

Editors’ Summary

Background.

Depressive disorders are common mental disorders that occur in people of all ages across all world regions. Depression—an overwhelming feeling of sadness and hopelessness that can last for months or years—can make people feel that life is no longer worth living. People affected by depression lose interest in the activities they used to enjoy and can also be affected by physical symptoms such as disturbed sleep. Major depressive disorder (MDD, also known as clinical depression) is

• an episodic disorder with a chronic (long-term) outcome and increased risk of death.

It involves at least one major depressive episode in which the affected individual experiences

• a depressed mood almost all day, every day for at least 2 weeks.

Dysthymia is a milder, chronic form of depression that lasts for at least 2 years. People with dysthymia are often described as constantly unhappy. Both these subtypes of depression (and others such as that experienced in bipolar disorder) can be treated with antidepressant drugs and with talking therapies.

Why Was This Study Done? Depressive disorders were a  leading cause of disease burden in the 1990 and 2000 Global Burden of Disease (GBD) studies, collaborative scientific efforts that quantify the health loss attributable to

• diseases and injuries in terms of disability adjusted life years (DALYs; one DALY represents the loss of a healthy year of life).

DALYs are calculated by adding together the years of life lived with a disability (YLD, a measure that includes a disability weight factor reflecting disease severity) and the years of life lost because of disorder-specific premature death. The GBD initiative aims

• to provide data that can be used to improve public-health policy.

Thus, knowing that depressive disorders are a leading cause of disease burden worldwide has helped to prioritize depressive disorders in global public-health agendas. Here, the researchers analyze the burden of MDD and dysthymia in GBD 2010 by country, region, age, and sex, and

• calculate the burden of suicide and ischemic heart disease attributable to depressive disorders (depression is a risk factor for suicide and ischemic heart disease).

GBD 2010 is broader in scope than previous GBD studies and quantifies the direct burden of 291 diseases and injuries and the  burden attributable to 67 risk factors across 187 countries.

What Did the Researchers Do and Find? The researchers collected data on

• the prevalence, incidence, remission rates, and duration of MDD and dysthymia and on deaths caused by these disorders from published articles.

They pooled these data using a statistical method called Bayesian meta-regression and calculated YLDs for MDD  and dysthymia using disability weights collected in population surveys. MDD accounted for 8.2% of global YLDs in 2010, making it the second leading cause of YLDs. Dysthymia accounted for 1.4% of global YLDs. MDD and dysthymia were also leading causes of DALYs, accounting for 2.5% and 0.5% of global DALYs, respectively. The regional variation in the burden was greater for MDD than for dysthymia, the  burden of depressive disorders was higher in women than men, the largest proportion of YLDs from depressive  disorders occurred among adults of working age, and the  global burden of depressive disorders increased by 37.5%  between 1990 and 2010 because of population growth and ageing. Finally, MDD explained an additional 16 million  DALYs and 4 million DALYs when it was considered as a risk factor for suicide and ischemic heart disease, respectively.  This ‘‘attributable’’ burden increased the overall burden of depressive disorders to 3.8% of global DALYs.

What Do These Findings Mean? These findings update and extend the information available from GBD 1990 and  2000 on the global burden of depressive disorders. They confirm that

• depressive disorders are a leading direct cause of the global disease burden and show that
• MDD also contributes to the burden allocated to suicide and ischemic heart disease.

The estimates of the global burden of depressive disorders reported in GBD 2010 are likely to be more accurate than those in previous GBD studies but are  limited by factors such as the sparseness of data on depressive disorders from developing countries and, consequently,

• the validity of the disability weights used to calculate YLDs.

Even so, these findings reinforce the importance of treating  depressive disorders as a public-health priority and

• of implementing cost-effective interventions to reduce their  ubiquitous burden.

Additional Information. Please access these websites via  the online version of this summary at http://dx.doi.org/10.1371/journal.pmed.1001547.