MedWire News: Depression is more damaging to health than other chronic diseases such as angina, arthritis, asthma, and diabetes, reports an international team of researchers.
They also report that comorbid depression is more damaging to health than depression alone, and say their findings show that improving the treatment of depression should be a public health priority.
Little previous research has sought to determine how overall health status is impacted by depression, either alone or as a comorbity, say the researchers.
The International Classification of Diseases-10 criteria were used to estimate the prevalence of depression. Algorithms developed from the Diagnostic Item Probability Study allowed researchers to calculate the prevalences of angina, arthritis, asthma, and diabetes. Factor analysis was used to construct average health scores, which were compared across different disease states and demographic variables.
The 1-year prevalence for a depressive episode alone was 3.2%, compared with 4.5% for angina, 4.1% for arthritis, 3.3% for asthma, and 2.0% for diabetes, the team writes in The Lancet.
Between 9.3% and 23.0% of patients with at least one chronic physical disease also had comorbid depression, which was significantly higher than the likelihood of having depression alone.
In comparison with the other chronic conditions studied, depression had the greatest impact on worsening average health scores, after adjusting for socioeconomic factors and health conditions, at overall health coefficients of -13.89 for depression alone versus -6.68 for angina alone, -5.92 for arthritis alone, -6.54 for asthma alone, and -3.53 for diabetes alone.
The team also found that, across all countries and demographic characteristics, comorbid depression with at least one chronic disease led to even worse overall heath scores, at a coefficient of -24.38 for depression plus at least one condition, -20.47 for depression plus angina -16.77 for depression plus arthritis, -19.44 for depression plus asthma, and -23.43 for depression plus diabetes.
The researchers conclude: "Our main findings show that depression impairs health state to a substantially greater degree than the other disease states. A significant percentage of respondents have depression in addition to their existing chronic physical conditions, a group that is often unrecognised and untreated.
"This finding is of special importance, considering the presence of depression and its treatment is clearly related to the outcome of these chronic diseases."
In an accompanying editorial, Gavin Andrews and Nickolai Titov, from the University of New South Wales in Sydney, Australia, comment: "The prevalence of depression is similar to the chronic physical disease studied, but the lifetime risk - the number of people who cycle in and out of depression - is five to 10 times greater than the lifetime risk of any of the other disease studied."
Journal
