October 16, 2007

Mental disorders account for about one-third of all sick days, roughly equal to those caused by back pain, according to the most comprehensive report yet on the effect of illness on disability. Transient illnesses, such as influenza, were not included in the survey.

Adult Americans with depression, anxiety or other psychological disorders annually miss 1.3 billion days of work, school or other daily activity, according to a report published this month in the Archives of General Psychiatry. Back and neck pain cause sufferers to miss 1.2 billion days.

Mental disorders had a bigger effect than expected, researchers said, yet they often are left unrecognized and untreated.

"If we treated the mental disorders, we could wipe out a lot of the impairment," said senior author Ronald C. Kessler, a professor of health-care policy at Harvard Medical School.

Lead author Kathleen Merikangas, an epidemiologist with the National Institute of Mental Health, said more funds should be allocated to the study and treatment of musculoskeletal conditions and depression and psychiatric disorders.

"It is ironic we spend the least on musculoskeletal disorders and depression when they have the most impact on people's lives and disability," she said.

The study was based on the National Comorbidity Survey Replication, a nationwide survey of 9,282 people over age 18 that was sponsored by the National Institute of Mental Health.

Participants reported the number of days they had been completely unable to work or carry out normal activities within the previous month. They also said which of 30 mental and physical conditions, including such illnesses as cancer and heart disease, they had had during the past year.

Taken together, all chronic conditions, including cancer, heart attack, ulcers and vision loss, sideline adults for a total of 3.7 billion days a year, researchers said.

Researchers found that more than half of American adults have chronic health conditions. Some go to work every day, while others are severely impaired and no longer work. The study found that those with chronic conditions take an average of 32 sick days a year.

Among mental disorders, depression accounted for the most sick days, at 387 million. Others reasons included social phobia, at 214 million days; post-traumatic stress disorder, 113 million; generalized anxiety disorder, 110 million; bipolar disorder, 103 million; panic disorders, 101 million; substance abuse, 93 million; agoraphobia, 37 million; and separation anxiety disorder, 20 million.

Besides back and neck pain, other physical conditions that led to missed days at work included arthritis, at 375 million days, and stroke, at 221 million days.

Cancer patients missed a total of 71.5 million days, and heart attack victims 204 million days.

Although the diseases are devastating, cancer and heart attacks accounted for a relatively low number of lost workdays.

Kessler explained that the diseases tend to strike older adults. In addition, cancer often does not affect the ability of people to function from day to day as much as back pain or depression.