4.5 times higher depending on the condition. Adults with multiple chronic conditions were 42.9 times more likely to have a disability than those without comorbidities (Zhao et al., 2009).1

Depression and Anxiety

Depression and anxiety can cause profound functional impairment. Major depressive disorder produces impairment in functioning as severe as other chronic medical illnesses, including cardiovascular disease (Hays et al., 1995; Kessler et al., 2003; Ormel et al., 2008; Papakostas, 2009). The World Health Organization reports that depression is the leading cause of years lost due to disability for both men and women worldwide, and projects that depression and heart disease will be the two leading causes of disability in developed countries in the next decade (WHO, 2008). When major psychiatric and medical disorders co-occur, the proportion of disability attributable to psychiatric comorbidity is often greater than that attributable to the medical illness (Kessler et al., 2003).

Having even a few depression symptoms can contribute significantly to functional impairment and disability, although the level of impairment increases with the severity of depression (Papakostas, 2009; Spertus et al., 2000). Mild levels of anxiety may actually encourage adherence to the cardiac treatment regimen and more attentiveness to potentially fatal symptoms of heart disease; whereas moderate to severe anxiety is likely to contribute to cardiac disability, excessive medical service use, and an increased risk of further cardiac morbidity and even mortality (Frasure-Smith and Lespérance, 2008; Shen et al., 2008; Shibeshi et al., 2007). Of the two, depression is more difficult to detect, and therefore less likely to be treated or even documented in medical records. Also, substantially more research has been done on depression than anxiety or other mental disorders. Therefore, depression will be considered here in some detail, followed by a short review of research on anxiety and coronary heart disease (CHD).

Epidemiology of Depression

Depression is common in patients with cardiovascular disease. For example, at any point in time about 15 to 20 percent of patients with docu-

1

The definition of disability in the Behavioral Risk Factor Surveillance System (BRFSS) is different from, i.e., less severe than, the Social Security Administration’s definition. The latter pertains to individuals unable to engage in any substantial gainful activities, while the BRFSS classifies respondents as disabled if they answer “yes” to either of two questions: “Are you limited in any way in any activities because of physical, mental, or emotional problems?” or “Do you now have any health problem that requires you to use special equipment, such as a cane, a wheelchair, a special bed, or a special telephone?” (CDC, 2010).



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