Depression Eclipses Other Chronic Disease for Poor Health Status

GENEVA, Switzerland, Sept. 7 -- No individual chronic disease -- not angina, not arthritis, not asthma, not diabetes -- is more disabling than depression, according to a World Health Organization study.
In the World Health Survey of 245,404 patients ages 18 and older, from 60 countries in all regions of the world. respondents with depression had the lowest health score among all five chronic disease conditions, 72.9 (P<0.0001).
On the basis of interviews and self-reports, respondents with asthma, angina, arthritis, or diabetes alone had mean health scores of 80.3, 79.6, 79.3, and 78.9, respectively, significantly different from having no disease, but not from one another, Somnath Chatterji, M.D., of the WHO here, and colleagues, reported in the Sept. 8 issue of The Lancet.
Patients with depression plus even one chronic disease had the worst scores on a health survey, they added. Respondents with neither chronic disease nor depression had the highest health score of 90.6.
Depression prevalence was determined on the basis of ICD-10 criteria, while the prevalence for four chronic physical diseases-angina, arthritis, asthma, and diabetes-was estimated from a Diagnostic Item Probability Study. Overall, the rate of a depressive episode in the previous year was 3.2% (95% CI 3.0-3.5).
For angina, this figure was 4.5% (4.3-4.8); for arthritis 4.1% (3.8-4.3); for asthma 3.3% (2.9-3.6); and for diabetes 2.0% (1.8-2.2).
The depression risks for these chronic diseases were higher than that expected in the general population, the researchers said.
The low 2% figures for diabetes, they commented, may have been based on self-reporting, and so bias could not be ruled out.
The researchers developed a new measure to estimate an individual's health or relative disability. The measure used 18 health-related questions pertaining to general health and disability in working or household activities. This was followed by 12 self-reported health questions including sleep, pain, cognition, self-care, vision, mobility, energy, and interpersonal activities.
A significant percentage of respondents with any one of the chronic physical conditions also had depression. For example, of those with diabetes, 9.3% also had depression. Of those with angina, 15% had depression. Of those with arthritis, 10.7% had depression, while those with asthma, had the highest depression prevalence at 18.1%.
For the 7.1% of respondents who had two or more chronic physical conditions, nearly a quarter (23%) also had depression.
An average of 9.3% to 23.0% of participants with at least one chronic physical disease had comorbid depression, which was significantly higher than the likelihood of having depression in the absence of a chronic physical disease (P<0.0001), the researchers said.
After adjustment for socioeconomic factors and health conditions, the researchers found that depression was significantly associated with worsening mean health scores in respondents with chronic conditions, compared with those having chronic conditions without depression (P<0.001).
In reviewing the study's limitations, the researchers said that because the World Health Survey was cross-sectional, they could not determine what burden depression combined with other chronic diseases places on the health care system.
It was also impossible to determine how depression can modify the course of these disorders, and whether treatment of depression when present with these chronic physical disorders would alter their course.
The need for timely diagnosis and treatment of depressive disorders is imperative for health-care systems worldwide, the researchers said.
"Primary-care providers need to think depression when patients have a chronic physical condition in view of the marked effect it has on an individual's health," they concluded.
In an accompanying commentary, Gavin Andrews, M.D., and Nickolai Titov, Ph.D., of the University of New South Wales in Sydney, Australia, wrote that depression is simple to recognize and not difficult to treat. Yet the burden persists.
If there were a laboratory test to confirm the diagnosis, doctors might be more assertive about insisting that patients adhere to treatment, they suggested.
In Australia, fewer than 30% of patients receive good treatment with antidepressants, cognitive behavioral therapy, and proactive maintenance care. By contrast, 80% of patients with arthritis and 90% of those with asthma receive an acceptable standard of care.
"Perhaps differential access to treatment is one reason why disability is less with the physical disorders. Treatment for depression should at least be on a par with that for other chronic diseases," they concluded.
This study was funded by the World Health Organization. No conflicts of interest were reported for the study or the Comment authors. Primary source: The LancetSource reference: Moussavi S et al "Depression, chronic diseases, and decrements in health: results from the World Health Surveys" The Lancet 2007; 370: 851-858. Additional source: The LancetSource reference: Andrews G, Titov, N "Depression is very disabling" The Lancet 2007; 370:808-809.