Depression should join the ranks of obesity, diabetes, hypertension, and smoking as an official heart disease risk factor, according to an expert panel convened by the American Heart Association (AHA).
The recommendation is based on an extensive literature review examining the risks for depression conducted by the panel, which included Robert M. Carney, PhD, professor of psychiatry at the Washington University School of Medicine in St. Louis, Missouri.
The AHA Scientific Statement notes that the combined findings support the call to formally "elevate depression to the status of a risk factor" for adverse outcomes, such as all-cause and cardiac mortality, in patients who have acute coronary syndrome (ACS).
"It was very gratifying to see this recommendation at this time and know that the potential risks are appreciated," Dr. Carney, who is also a member of the AHA Statistics Committee of the Council on Epidemiology and Prevention and the Council on Cardiovascular and Stroke Nursing, told Medscape Medical News.
"We're hoping that eventually we'll be able to show that treating depression will improve survival and heart health. Although that story remains to be done, I'm happy we've come this far," Dr. Carney added.
The Scientific Statement was published online February 24 in Circulation.
According to the investigators, approximately 20% of all patients who have ACS, myocardial infarction (MI), or unstable angina also meet clinical criteria for major depression, and many more of these patients have depressive symptoms.
As reported by Medscape Medical News, recent studies have shown that chronic episodes of depression may be causally linked to an increased risk for coronary heart disease and that major depression is now the second leading cause of disability and is a major contributor to ischemic heart disease.
Last year, Angelos Halaris, MD, PhD, professor in the Department of Psychiatry and Behavioral Neurosciences at Loyola University Stritch School of Medicine in Maywood, Illinois, went so far as to suggest the creation of a new "psychocardiology" subspecialty that would specifically address the association often found between depression and heart disease.
The current researchers note that although many studies over the years have shown a strong association between depression and increased morbidity after experiencing ACS, depression has not been recognized as a formal risk factor by national health organizations.
Dr. Carney and colleagues published their first article showing that depression doubles the risk for cardiac events in patients with recently diagnosed heart disease in 1988. "So we've been working on this problem for a long time."
He reported that AHA recently contacted several scientists who had done research in this area and asked them to convene and critically review the current literature to see whether depression should be elevated to the status of a risk factor for adverse outcomes "rather than just something to keep your eye on."
The 12-member panel examined 53 individual studies that looked at associations between depression and all-cause mortality, cardiac mortality, and/or composite outcomes that included both mortality and nonfatal events.
Each of these English-language studies had a prospective design and included at least 100 patients recovering from ACS. Four meta-analyses that examined these relationships in patients with ACS or other coronary heart disease diagnoses were also reviewed.
"Many studies have reported that depression predicts increased mortality, but it's rare to delve into this kind of research as deeply and as carefully as we have," said Dr. Carney in a release.
Formal Recognition Warranted
Thirty-two of the studies examined all-cause mortality in 22 unique patient cohorts from 9 countries in North America, Europe, and Asia. Sample sizes ranged from 100 to 21,745 participants, and follow-ups ranged from 1 month to 10 years.
Results showed that 17 of the studies found a significant risk-adjusted association between depression and increased risk for all-cause mortality after ACS, and 4 of the studies showed a significant unadjusted association.
The review also included 12 studies that examined cardiac mortality in 8 unique patient cohorts from 5 countries, with sample sizes ranging from 222 to 1042. Seven of these studies showed a significant risk-adjusted association, and 1 had a significant unadjusted association between depression and increased cardiac mortality.
When examining the studies that included composite outcomes, the investigators found that the majority showed a significant association with depression.
Three of the meta-analyses, which were published through 2003, showed overall unadjusted effects ranging from 1.8 to 2.6 for all cause-mortality and from 2.3 to 2.9 for cardiac mortality.
The fourth meta-analysis assessed studies published through January 2011 of patients who only had MI. It showed unadjusted effects of 2.3, 2.7, and 1.6 for all-cause mortality, cardiac mortality, and composite outcomes, respectively.
"Despite the heterogeneity of published studies included in this review, the preponderance of evidence" supports the recommendation that depression should be formally added to the list of risk factors for ACS.
Dr. Carney added that not every study included in this review showed that depression predicts mortality or heart problems, "but most of them did."
However, he noted that there are currently no good data on whether treating depression will actually lower cardiac risk or improve survival.
"The evidence supports that depression is a risk factor. But I can't tell a clinician that treating it will improve survival in the patient. Certainly many of us believe that it probably will, but until studies are done, we just don't know," said Dr. Carney.
"But we have every reason to believe that it can improve quality of life in these patients. And we think that that is a very important reason to consider treatment in itself."
Need for Routine Screening
"This Scientific Statement by the American Heart Association is a very important step," Wayne Katon, MD, professor and vice-chair in the Department of Psychiatry and Behavioral Sciences at the University of Washington School of Medicine in Seattle, told Medscape Medical News.
Dr. Katon, who was not involved with this research, noted that there have been multiple studies showing that depression is associated with risk for mortality in people who have MI.
"But until it comes out as a risk factor, an association doesn't infer causality. Now, based on the review, it's come out officially that it is a risk factor," he said.
"This is important because until recently, cardiologists would screen for other risk factors, such as the Framingham risk factors. But now that depression has made it onto the same table, I would hope that cardiologists would routinely also screen for depression."
He added that there are some "very good" depression screening measures, such as the Patient Health Questionnaire (PHQ-9), which has been widely used in primary care settings.
However, he noted that after screening, it is important to figure out how to implement treatment. Although cardiologists often make a mental health referral for patients with depression, many of these patients do not follow through because of stigma, lack of insurance coverage, or other reasons.
"So we and others have pioneered ways of treating depression in primary care settings. And [colleagues] have adapted those methods for treating cardiac patients," said Dr. Katon.
"But there's no doubt that new research needs to be done to develop ways to better treat this newly recognized risk factor and ways to do collaborative care within cardiology practices," he said.
In 2010, as reported by Medscape Medical News, Dr. Katon and colleagues found that a coordinated care management program improved disease control and decreased adverse outcomes in patients with both depression and other chronic conditions, including diabetes and coronary heart disease.
"We used a multicondition collaborative care intervention where we aimed to improve depression but also patient adherence and treatment for their medical condition. We were able to show not only that we improved outcomes but also quality of life functioning, and we saved costs," he explained.
"So if you do the right intervention, you not only improve outcomes and patient satisfaction, but you also save money for health care systems."
Circulation. Published online February 24, 2014. Full text
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Cite this: List Depression as Official Heart Disease Risk Factor, AHA Panel Says - Medscape - Feb 28, 2014.