Several research studies have shown that the percent of depressed individuals who are treated for their depression is less than 50%. We use a default of 50% in the model in order to be conservative. This rate is also closer to the most recent population estimate provided in the Kessler article summarized below.

Kessler RC, Berglund P, Demler O, et al. The epidemiology of major depressive disorder. Journal of the American Medical Association, 2003; 289(23): 3095-3105.
This is the most recent nationally representative study to provide data on prevalence and treatment of depression. The authors found that 57.3% of respondents with 12-month major depressive disorder received some type of treatment in the 12 months before their interview, and concluded that “no more than 21.6% of all respondents received adequate treatment in the year of the interview.” They also found that 29.5% of those with “very severe” depression had received no treatment at all.

Mental Health: A Report of the Surgeon General, Chapter 6: Organizing and Financing Mental Health Services. Available online at http://www.surgeongeneral.gov/library/mentalhealth/chapter6/sec1.html
The Surgeon General Report on mental health shows that of the U.S. population with mental/addictive disorders, 71% receive no treatment. Although the report does not show treatment rates for depression alone, the estimate for depressive disorders is probably less than 71%.

Young AS, Klap R, Sherbourne CD, Wells KB. The quality of care for depressive and anxiety disorders in the United States, Archives of General Psychiatry, 2001; 58: 55-61.
In this cross-sectional telephone survey during 1997-1998 of 1,636 adults with a probably 12-month depressive or anxiety disorder, appropriate treatment was received by only 30.4% of individuals.

Stewart WF, Ricci JA, Chee E, Hahn SR, Morganstein D (2003). Cost of lost productive work time among US workers with depression. Journal of the American Medical Association, 289(23): 3135-3144.
Data were analyzed from employees who participated in the American Productivity Audit in 2001-2002. Less than 30% of those with depression had used antidepressants in the previous 12 months. The authors did not provide information regarding psychotherapy treatment.

Goetzel RZ, Ozminkowski RJ, Sederer LI, Mark TL. Working with depression, part I: The business case for quality mental health services. Business and Health, 2002; August.
The authors review recent work on the diagnosis and treatment of depression in relation to work productivity. They state “only about a third of patients suffering from clinical depression receive appropriate medication or psychotherapy.”

Riotto M. Depression in the workplace. Benefits Quarterly, 2001; 2: 37-48.
In the author’s review of data from clinical studies, he states “major depression is unrecognized or misdiagnosed in about 50% to 75% of affected individuals.”

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