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Mental Disorders Account for Large Percentage of Adult Role Disability

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Science Update

An NIMH-funded study finds that more than half of U.S. adults have a mental or physical condition that prevents them from working or conducting their usual duties (e.g., role disability) for several days each year, and a large portion of those days can be attributed to mental disorders. The study, published in the October 2007 issue of the Archives of General Psychiatry, is based on data from the National Comorbidity Survey Replication (NCS-R), a nationwide survey among 9,282 Americans ages 18 and older.

Role disability is increasingly recognized as a major source of the societal costs of illness, but these indirect costs—the result of impaired functioning and lost productivity—are not easily measured, making it difficult to estimate the total costs of illness. To help quantify these costs, NIMH researcher Kathleen Merikangas, PhD., Ronald Kessler, PhD., of Harvard University, and colleagues analyzed data from 5,962 respondents of the NCS-R to determine the rate and frequency of role disability. They asked respondents how many days they were completely unable to work or carry out their usual activities as a result of a mental or chronic physical condition, such as an anxiety or mood disorder, substance or alcohol dependence, cancer, cardiovascular illness, musculoskeletal conditions, or others.

They found that over a one-year period, 53 percent of U.S. adults have one or more mental or physical conditions that result in role disability. Among those adults, each experienced an average of 32 days of disability per year. Nationwide, about 2.4 billion disability days resulted from physical conditions, and about 1.3 billion disability days resulted from mental conditions. “These figures suggest an enormous burden on the people who have one or more of these conditions, their families and their employers,” said Dr. Merikangas.

Estimating the impact of specific diseases on disability is difficult because people tend to have more than one illness or disorder at a time, such as depression and heart disease. By accounting for the likelihood of coexisting disorders, the authors found that musculoskeletal disorders, especially back and neck pain, resulted in the greatest number of disability days (1.2 billion) while major depression resulted in the second greatest number of disability days (387 million).

This research documents that the level of disability associated with chronic mental conditions is as large as that associated with many chronic physical conditions.  By documenting the impact and cost of chronic mental and physical disorders, this research may be useful to health care providers and policymakers.

Reference

Merikangas KR. Ames M, Cui L, Stang PE, Ustun TB, von Korff M, Kessler, RC. The impact of comorbidity of mental and physical conditions on role disability in the US adult population. Archives of General Psychiatry, Oct 2007; VOL 64(10).